Method for selective immobilization of macromolecules on self assembled monolayer surfaces

Science.gov (United States)

Laskin, Julia [Richland, WA; Wang, Peng [Billerica, MA

2011-11-29

Disclosed is a method for selective chemical binding and immobilization of macromolecules on solid supports in conjunction with self-assembled monolayer (SAM) surfaces. Immobilization involves selective binding of peptides and other macromolecules to SAM surfaces using reactive landing (RL) of mass-selected, gas phase ions. SAM surfaces provide a simple and convenient platform for tailoring chemical properties of a variety of substrates. The invention finds applications in biochemistry ranging from characterization of molecular recognition events at the amino acid level and identification of biologically active motifs in proteins, to development of novel biosensors and substrates for stimulated protein and cell adhesion.

Selective formation of diamond-like carbon coating by surface catalyst patterning

DEFF Research Database (Denmark)

Palnichenko, A.V.; Mátéfi-Tempfli, M.; Mátéfi-Tempfli, Stefan

2004-01-01

The selective formation of diamond-like carbon coating by surface catalyst patterning was studied. DLC films was deposited using plasma enhanced chemical vapor deposition, filtered vacuum arc deposition, laser ablation, magnetron sputtering and ion-beam lithography methods. The DLC coatings were...

Tribochemical interaction between nanoparticles and surfaces of selective layer during chemical mechanical polishing

International Nuclear Information System (INIS)

Ilie, Filip

2013-01-01

Nanoparticles have been widely used in polish slurries such as those in the chemical mechanical polishing (CMP) process. For understanding the mechanisms of CMP, an atomic force microscope (AFM) is used to characterize polished surfaces of selective layers, after a set of polishing experiments. To optimize the CMP polishing process, one needs to get information on the interaction between the nano-abrasive slurry nanoparticles and the surface of selective layer being polished. The slurry used in CMP process of the solid surfaces is slurry with large nanoparticle size colloidal silica sol nano-abrasives. Silica sol nano-abrasives with large nanoparticle are prepared and characterized by transmission electron microscopy, particles colloidal size, and Zeta potential in this paper. The movement of nanoparticles in liquid and the interaction between nanoparticles and solid surfaces coating with selective layer are very important to obtain an atomic alloy smooth surface in the CMP process. We investigate the nanoparticle adhesion and removal processes during CMP and post-CMP cleaning. The mechanical interaction between nanoparticles and the wafer surface was studied using a microcontact wear model. This model considers the nanoparticle effects between the polishing interfaces during load balancing. Experimental results on polishing and cleaning are compared with numerical analysis. This paper suggests that during post-CMP cleaning, a combined effort in chemical and mechanical interaction (tribochemical interactions) would be effective in removal of small nanoparticles during cleaning. For large nanoparticles, more mechanical forces would be more effective. CMP results show that the removal rate has been improved to 367 nm/min and root mean square (RMS) of roughness has been reduced from 4.4 to 0.80 nm. Also, the results show that the silica sol nano-abrasives about 100 nm are of higher stability (Zeta potential is −65 mV) and narrow distribution of nanoparticle

Laser-induced selective copper plating of polypropylene surface

Science.gov (United States)

Ratautas, K.; Gedvilas, M.; Stankevičiene, I.; JagminienÄ--, A.; Norkus, E.; Li Pira, N.; Sinopoli, S.; Emanuele, U.; Račiukaitis, G.

2016-03-01

Laser writing for selective plating of electro-conductive lines for electronics has several significant advantages, compared to conventional printed circuit board technology. Firstly, this method is faster and cheaper at the prototyping stage. Secondly, material consumption is reduced, because it works selectively. However, the biggest merit of this method is potentiality to produce moulded interconnect device, enabling to create electronics on complex 3D surfaces, thus saving space, materials and cost of production. There are two basic techniques of laser writing for selective plating on plastics: the laser-induced selective activation (LISA) and laser direct structuring (LDS). In the LISA method, pure plastics without any dopant (filler) can be used. In the LDS method, special fillers are mixed in the polymer matrix. These fillers are activated during laser writing process, and, in the next processing step, the laser modified area can be selectively plated with metals. In this work, both methods of the laser writing for the selective plating of polymers were investigated and compared. For LDS approach, new material: polypropylene with carbon-based additives was tested using picosecond and nanosecond laser pulses. Different laser processing parameters (laser pulse energy, scanning speed, the number of scans, pulse durations, wavelength and overlapping of scanned lines) were applied in order to find out the optimal regime of activation. Areal selectivity tests showed a high plating resolution. The narrowest width of a copper-plated line was less than 23 μm. Finally, our material was applied to the prototype of the electronic circuit board on a 2D surface.

The role of surface chemical analysis in a study to select replacement processes for TCA vapor degreasing

Science.gov (United States)

Lesley, Michael W.; Davis, Lawrence E.; Moulder, John F.; Carlson, Brad A.

1995-01-01

The role of surface-sensitive chemical analysis (ESCA, AES, and SIMS) in a study to select a process to replace 1, 1, 1-trichloroethane (TCA) vapor degreasing as a steel and aluminum bonding surface preparation method is described. The effort was primarily concerned with spray-in-air cleaning processes involving aqueous alkaline and semi-aqueous cleaners and a contamination sensitive epoxy-to-metal bondline. While all five cleaners tested produced bonding strength results equal to or better than those produced by vapor degreasing, the aqueous alkaline cleaners yielded results which were superior to those produced by the semi-aqueous cleaners. The main reason for the enhanced performance appears to be a silicate layer left behind by the aqueous alkaline cleaners. The silicate layer increases the polarity of the surface and enhances epoxy-to-metal bonding. On the other hand, one of the semi-aqueous cleaners left a nonpolar carbonaceous residue which appeared to have a negative effect on epoxy-to-metal bonding. Differences in cleaning efficiency between cleaners/processes were also identified. These differences in surface chemistry, which were sufficient to affect bonding, were not detected by conventional chemical analysis techniques.

Selective deoxygenation of aldehydes and alcohols on molybdenum carbide (Mo2C) surfaces

International Nuclear Information System (INIS)

Xiong, Ke; Yu, Weiting; Chen, Jingguang G.

2014-01-01

Highlights: • Mo 2 C surface can deoxygenate propanal and 1-propanol to produce propene through a similar intermediate (propoxide or η 2 (C,O)-propanal). • Mo 2 C surface can deoxygenate furfural and furfuryl alcohol to make 2-methylfuran through a 2-methylfuran-like intermediate. • The presence of furan ring modifies the selectivity between deoxygenation and hydrogenation/dehydrogenation pathways. - Abstract: The selective deoxygenation of aldehydes and alcohols without cleaving the C-C bond is crucial for upgrading bio-oil and other biomass-derived molecules to useful fuels and chemicals. In this work, propanal, 1-propanol, furfural and furfuryl alcohol were selected as probe molecules to study the deoxygenation of aldehydes and alcohols on molybdenum carbide (Mo 2 C) prepared over a Mo(1 1 0) surface. The reaction pathways were investigated using temperature programmed desorption (TPD) and high resolution electron energy loss spectroscopy (HREELS). The deoxygenation of propanal and 1-propanol went through a similar intermediate (propoxide or η 2 (C,O)-propanal) to produce propene. The deoxygenation of furfural and furfuryl alcohol produced a surface intermediate similar to adsorbed 2-methylfuran. The comparison of these results revealed the promising deoxygenation performance of Mo 2 C, as well as the effect of the furan ring on the selective deoxygenation of the C=O and C-OH bonds

Application of high Tc superconductors as frequency selective surfaces: Experiment and theory

International Nuclear Information System (INIS)

Dawei Zhang; Yahya Rahmat-Samii; Fetterman, H.R.

1993-01-01

YBa 2 Cu 3 O 7-x and Tl 2 CaBa 2 Cu 2 O 8 high temperature superconducting thin films were utilized to fabricate frequency selective surfaces (FSS) at millimeter-wave frequencies (75--110 GHz). An analytical/numerical model was applied, using a Floquet expansion and the Method of Moments, to analyze bandstop superconducting frequency selective surfaces. Experimental results were compared with the model, and showed a good agreement with resonant frequency prediction with an accuracy of better than 1%. The use of the superconducting frequency selective surfaces as quasi-optical millimeter-wave bandpass filters was also demonstrated

Color selectivity of surface-plasmon holograms illuminated with white light.

Science.gov (United States)

Ozaki, Miyu; Kato, Jun-ichi; Kawata, Satoshi

2013-09-20

By using the optical frequency dependence of surface-plasmon polaritons, color images can be reconstructed from holograms illuminated with white light. We report details on the color selectivity of the color holograms. The selectivity is tuned by the thickness of a dielectric film covering a plasmonic metal film. When the dielectric is SiO(2) and the metal is silver, the appropriate thicknesses are 25 and 55 nm, respectively. In terms of spatial color uniformity, holograms made of silver-film corrugations are better than holograms recorded on photographic film on a flat silver surface.

Spatial Tuning of a RF Frequency Selective Surface through Origami (Postprint)

Science.gov (United States)

2016-05-12

computational tools to systematically predict optimal folds. 15. SUBJECT TERMS origami, frequency selective surface, tuning, radio frequency 16...experimental study and motivates the development of computational tools to systematically predict optimal fold patterns for targeted frequency response...folding motions. The precise mapping of origami presents a novel method to spatially tune radio frequency (RF) devices, including adaptive antennas

Selective albumin-binding surfaces modified with a thrombin-inhibiting peptide.

Science.gov (United States)

Freitas, Sidónio C; Maia, Sílvia; Figueiredo, Ana C; Gomes, Paula; Pereira, Pedro J B; Barbosa, Mário A; Martins, M Cristina L

2014-03-01

Blood-contacting medical devices have been associated with severe clinical complications, such as thrombus formation, triggered by the activation of the coagulation cascade due to the adsorption of certain plasma proteins on the surface of biomaterials. Hence, the coating of such surfaces with antithrombotic agents has been used to increase biomaterial haemocompatibility. Biomaterial-induced clotting may also be decreased by albumin adsorption from blood plasma in a selective and reversible way, since this protein is not involved in the coagulation cascade. In this context, this paper reports that the immobilization of the thrombin inhibitor D-Phe-Pro-D-Arg-D-Thr-CONH2 (fPrt) onto nanostructured surfaces induces selective and reversible adsorption of albumin, delaying the clotting time when compared to peptide-free surfaces. fPrt, synthesized with two glycine residues attached to the N-terminus (GGfPrt), was covalently immobilized onto self-assembled monolayers (SAMs) having different ratios of carboxylate-hexa(ethylene glycol)- and tri(ethylene glycol)-terminated thiols (EG6-COOH/EG3) that were specifically designed to control GGfPrt orientation, exposure and density at the molecular level. In solution, GGfPrt was able to inactivate the enzymatic activity of thrombin and to delay plasma clotting time in a concentration-dependent way. After surface immobilization, and independently of its concentration, GGfPrt lost its selectivity to thrombin and its capacity to inhibit thrombin enzymatic activity against the chromogenic substrate n-p-tosyl-Gly-Pro-Arg-p-nitroanilide. Nevertheless, surfaces with low concentrations of GGfPrt could delay the capacity of adsorbed thrombin to cleave fibrinogen. In contrast, GGfPrt immobilized in high concentrations was found to induce the procoagulant activity of the adsorbed thrombin. However, all surfaces containing GGfPrt have a plasma clotting time similar to the negative control (empty polystyrene wells), showing resistance to

Selective deoxygenation of aldehydes and alcohols on molybdenum carbide (Mo{sub 2}C) surfaces

Energy Technology Data Exchange (ETDEWEB)

Xiong, Ke [Catalysis Center for Energy Innovation, Chemical and Biomolecular Engineering, University of Delaware, Newark, DE 19716 (United States); Yu, Weiting [Chemical Engineering, Columbia University, New York, NY 10027 (United States); Chen, Jingguang G., E-mail: jgchen@columbia.edu [Chemical Engineering, Columbia University, New York, NY 10027 (United States)

2014-12-30

Highlights: • Mo{sub 2}C surface can deoxygenate propanal and 1-propanol to produce propene through a similar intermediate (propoxide or η{sup 2}(C,O)-propanal). • Mo{sub 2}C surface can deoxygenate furfural and furfuryl alcohol to make 2-methylfuran through a 2-methylfuran-like intermediate. • The presence of furan ring modifies the selectivity between deoxygenation and hydrogenation/dehydrogenation pathways. - Abstract: The selective deoxygenation of aldehydes and alcohols without cleaving the C-C bond is crucial for upgrading bio-oil and other biomass-derived molecules to useful fuels and chemicals. In this work, propanal, 1-propanol, furfural and furfuryl alcohol were selected as probe molecules to study the deoxygenation of aldehydes and alcohols on molybdenum carbide (Mo{sub 2}C) prepared over a Mo(1 1 0) surface. The reaction pathways were investigated using temperature programmed desorption (TPD) and high resolution electron energy loss spectroscopy (HREELS). The deoxygenation of propanal and 1-propanol went through a similar intermediate (propoxide or η{sup 2}(C,O)-propanal) to produce propene. The deoxygenation of furfural and furfuryl alcohol produced a surface intermediate similar to adsorbed 2-methylfuran. The comparison of these results revealed the promising deoxygenation performance of Mo{sub 2}C, as well as the effect of the furan ring on the selective deoxygenation of the C=O and C-OH bonds.

Surface adhesins and exopolymers of selected foodborne pathogens

DEFF Research Database (Denmark)

Jaglic, Zoran; Desvaux, Mickaël; Weiss, Agnes

2014-01-01

The ability of bacteria to bind different compounds and to adhere to biotic and abiotic surfaces provides them with a range of advantages, such as colonization of various tissues, internalisation, avoidance of an immune response and survival and persistence in the environment. A variety of bacter......The ability of bacteria to bind different compounds and to adhere to biotic and abiotic surfaces provides them with a range of advantages, such as colonization of various tissues, internalisation, avoidance of an immune response and survival and persistence in the environment. A variety...... of bacterial surface structures are involved in this process and these promote bacterial adhesion in a more or less specific manner. In this review, we will focus on those surface adhesins and exopolymers in selected foodborne pathogens that are involved mainly in primary adhesion. Their role in biofilm...

Frequency selective surfaces integrated with phased array antennas

NARCIS (Netherlands)

Monni, S.

2005-01-01

Frequency Selective Surfaces (FSS's) are periodic arrays of patches and/or slots etched on a metal plate, having frequency and angular ??ltering properties. The FSS response to an excitation (for example a plane wave) is characterized in terms of its re ection and transmission coe??cient, and

Surface-site-selective study of valence electronic states of a clean Si(111)-7x7 surface using Si L23VV Auger electron and Si 2p photoelectron coincidence measurements

International Nuclear Information System (INIS)

Kakiuchi, Takuhiro; Tahara, Masashi; Nagaoka, Shin-ichi; Hashimoto, Shogo; Fujita, Narihiko; Tanaka, Masatoshi; Mase, Kazuhiko

2011-01-01

Valence electronic states of a clean Si(111)-7x7 surface are investigated in a surface-site-selective way using high-resolution coincidence measurements of Si pVV Auger electrons and Si 2p photoelectrons. The Si L 23 VV Auger electron spectra measured in coincidence with energy-selected Si 2p photoelectrons show that the valence band at the highest density of states in the vicinity of the rest atoms is shifted by ∼0.95 eV toward the Fermi level (E F ) relative to that in the vicinity of the pedestal atoms (atoms directly bonded to the adatoms). The valence-band maximum in the vicinity of the rest atoms, on the other hand, is shown to be shifted by ∼0.53 eV toward E F relative to that in the vicinity of the pedestal atoms. The Si 2p photoelectron spectra of Si(111)-7x7 measured in coincidence with energy-selected Si L 23 VV Auger electrons identify the topmost surface components, and suggest that the dimers and the rest atoms are negatively charged while the pedestal atoms are positively charged. Furthermore, the Si 2p-Si L 23 VV photoelectron Auger coincidence spectroscopy directly verifies that the adatom Si 2p component (usually denoted by C 3 ) is correlated with the surface state just below E F (usually denoted by S 1 ), as has been observed in previous angle-resolved photoelectron spectroscopy studies.

The importance of surface morphology in controlling the selectivity of polycrystalline copper for CO(2) electroreduction

DEFF Research Database (Denmark)

Tang, Wei; Peterson, Andrew A; Varela Gasque, Ana Sofia

2012-01-01

This communication examines the effect of the surface morphology of polycrystalline copper on electroreduction of CO(2). We find that a copper nanoparticle covered electrode shows better selectivity towards hydrocarbons compared with the two other studied surfaces, an electropolished copper elect...

A DFT study and micro-kinetic analysis of acetylene selective hydrogenation on Pd-doped Cu(111) surfaces

International Nuclear Information System (INIS)

Ma, Ling-Ling; Lv, Cun-Qin; Wang, Gui-Chang

2017-01-01

Semi-hydrogenation of acetylene in a hydrogen-rich stream is an industrially important process. Inspired by the recent experiments that Cu(111) surface doped by a small number of Pd atoms can exhibit excellent catalytic performance toward the dissociation of H_2 molecule as well as the high selective hydrogenation of acetylene as compared with pure Cu and Pd metal alone at low-temperature, here we performed systematic first-principles calculations to investigate the corresponding reaction mechanism related to the acetylene hydrogenation processes on single atom alloys (SAAs) and monolayer Pd/Cu(111) (i.e.,1.00 ML Pd/Cu(111)) model catalysts in detail, and to explore the possible factors controlling the high selectivity on SAAs. Our results clearly demonstrate that the SAA catalyst has higher selectivity for the ethylene formation than that of 1.00 ML Pd/Cu(111), and lower activity for the acetylene conversion compared with that of 1.00 ML Pd/Cu(111). The relatively high selectivity on SAA is mainly due to the facile desorption of ethylene and moderate activity in the dissociation of molecular H_2. The main factor which lowers the selectivity towards the ethylene formation on 1.00 ML Pd/Cu(111) is that this system has a higher capacity to promote the breaking of C−H/C−C bonds, which leads to the formation of carbonaceous deposits and polymers such as benzene, and thus reduces the selectivity for the ethylene formation. Meanwhile, it was found that the desorption energy of ethylene on these two surfaces was smaller than the energy barrier of further hydrogenation, which results in the absence of ethane on these two systems. Micro-kinetic model analysis provides a further valuable insight into the evidence for the key factors controlling the catalytic activity and selectivity towards the selective hydrogenation of acetylene. Our findings may help people to design a highly selective hydrogenation catalyst by controlling the balance between the H_2 dissociation and

A DFT study and micro-kinetic analysis of acetylene selective hydrogenation on Pd-doped Cu(111) surfaces

Science.gov (United States)

Ma, Ling-Ling; Lv, Cun-Qin; Wang, Gui-Chang

2017-07-01

Semi-hydrogenation of acetylene in a hydrogen-rich stream is an industrially important process. Inspired by the recent experiments that Cu(111) surface doped by a small number of Pd atoms can exhibit excellent catalytic performance toward the dissociation of H2 molecule as well as the high selective hydrogenation of acetylene as compared with pure Cu and Pd metal alone at low-temperature, here we performed systematic first-principles calculations to investigate the corresponding reaction mechanism related to the acetylene hydrogenation processes on single atom alloys (SAAs) and monolayer Pd/Cu(111) (i.e.,1.00 ML Pd/Cu(111)) model catalysts in detail, and to explore the possible factors controlling the high selectivity on SAAs. Our results clearly demonstrate that the SAA catalyst has higher selectivity for the ethylene formation than that of 1.00 ML Pd/Cu(111), and lower activity for the acetylene conversion compared with that of 1.00 ML Pd/Cu(111). The relatively high selectivity on SAA is mainly due to the facile desorption of ethylene and moderate activity in the dissociation of molecular H2. The main factor which lowers the selectivity towards the ethylene formation on 1.00 ML Pd/Cu(111) is that this system has a higher capacity to promote the breaking of Csbnd H/Csbnd C bonds, which leads to the formation of carbonaceous deposits and polymers such as benzene, and thus reduces the selectivity for the ethylene formation. Meanwhile, it was found that the desorption energy of ethylene on these two surfaces was smaller than the energy barrier of further hydrogenation, which results in the absence of ethane on these two systems. Micro-kinetic model analysis provides a further valuable insight into the evidence for the key factors controlling the catalytic activity and selectivity towards the selective hydrogenation of acetylene. Our findings may help people to design a highly selective hydrogenation catalyst by controlling the balance between the H2 dissociation and

Development of Surface-Modified Polyacrylonitrile Fibers and Their Selective Sorption Behavior of Precious Metals

Directory of Open Access Journals (Sweden)

Areum Lim

2016-11-01

Full Text Available The purpose of this study was to design a powerful fibrous sorbent for recovering precious metals such as Pd(II and Pt(IV, and moreover for identifying its selectivity toward Pd(II or Pt(IV from a binary metal solution. For the development of the sorbent, polyacrylonitrile (PAN was selected as a model textile because its morphological property (i.e., thin fiber form is suitable for fast adsorption processes, and a high amount of PAN has been discharged from industrial textile factories. The PAN fiber was prepared by spinning a PAN–dimethylsulfoxide mixture into distilled water, and then its surface was activated through amidoximation so that the fiber surface could possess binding sites for Pd(II and Pt(IV. Afterwards, by Fourier-transform infrared (FT-IR and scanning electron microscopy (SEM analyses, it was confirmed that the amidoximation reaction successfully occurred. The surface-activated fiber, designated as PAN–oxime fiber, was used to adsorb and recover precious metals. In the experiment results, it was clearly observed that adsorption capacity of PAN–oxime fiber was significantly enhanced compared to the raw material form. Actually, the raw material does not have sorption capacity for the metals. In a comparison study with commercial sorbent (Amberjet™ 4200, it was found that adsorption capacity of PAN–oxime was rather lower than that of Amberjet™ 4200, however, in the aspects of sorption kinetics and metal selectivity, the new sorbent has much faster and better selectivity.

Selection of conformational states in surface self-assembly for a molecule with eight possible pairs of surface enantiomers

DEFF Research Database (Denmark)

Nuermaimaiti, Ajiguli; Schultz-Falk, Vickie; Lind Cramer, Jacob

2016-01-01

Self-assembly of a molecule with many distinct conformational states, resulting in eight possible pairs of surface enantiomers, is investigated on a Au(111) surface under UHV conditions. The complex molecule is equipped with alkyl and carboxyl moieties to promote controlled self-assembly of lamel......Self-assembly of a molecule with many distinct conformational states, resulting in eight possible pairs of surface enantiomers, is investigated on a Au(111) surface under UHV conditions. The complex molecule is equipped with alkyl and carboxyl moieties to promote controlled self......-assembly of lamellae structures. From statistical analysis of Scanning Tunnelling Microscopy (STM) data we observe a clear selection of specific conformational states after self-assembly. Using Density Functional Theory (DFT) calculations we rationalise how this selection is correlated to the orientation of the alkyl...

Comprehensive study of rheological and surface properties of the selected slag system in the context of its internal structure

Directory of Open Access Journals (Sweden)

L. Řeháčková

2016-10-01

Full Text Available Rheological (dynamic viscosity, flow curves and surface properties (surface tension of real slag system were experimentally investigated. Measurements of dynamic viscosity were performed with use of the high-temperature viscometer Anton Paar FRS 1 600. The method of sessile drop was used for measurement of surface tension. Surface tension and dynamic viscosity were measured in the temperature interval from 1 200 to 1 600 °C. The structural characteristics of the selected samples were determined by X-ray diffraction (XRD. The samples for given analysis were prepared by quench cooling. Experimentally determined values of dynamic viscosity and surface tension were compared with the results of X-ray diffraction phase analysis.

Migration characterization of Ga and In adatoms on dielectric surface in selective MOVPE

International Nuclear Information System (INIS)

Chen Wei-Jie; Han Xiao-Biao; Lin Jia-Li; Hu Guo-Heng; Liu Ming-Gang; Yang Yi-Bin; Chen Jie; Wu Zhi-Sheng; Zhang Bai-Jun; Liu Yang

2015-01-01

Migration characterizations of Ga and In adatoms on the dielectric surface in selective metal organic vapor phase epitaxy (MOVPE) were investigated. In the typical MOVPE environment, the selectivity of growth is preserved for GaN, and the growth rate of GaN micro-pyramids is sensitive to the period of the patterned SiO 2 mask. A surface migration induced model was adopted to figure out the effective migration length of Ga adatoms on the dielectric surface. Different from the growth of GaN, the selective area growth of InGaN on the patterned template would induce the deposition of InGaN polycrystalline particles on the patterned SiO 2 mask with a long period. It was demonstrated with a scanning electron microscope and energy dispersive spectroscopy that the In adatoms exhibit a shorter migration length on the dielectric surface. (paper)

A DFT study and micro-kinetic analysis of acetylene selective hydrogenation on Pd-doped Cu(111) surfaces

Energy Technology Data Exchange (ETDEWEB)

Ma, Ling-Ling [Department of Chemistry, Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education) and Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Nankai University, Tianjin 300071 (China); Lv, Cun-Qin, E-mail: lcq173@126.com [College of Chemistry and Environmental Engineering, Shanxi Datong University, Datong 037009, Shanxi Province (China); Wang, Gui-Chang, E-mail: wangguichang@nankai.edu.cn [Department of Chemistry, Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education) and Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Nankai University, Tianjin 300071 (China)

2017-07-15

Semi-hydrogenation of acetylene in a hydrogen-rich stream is an industrially important process. Inspired by the recent experiments that Cu(111) surface doped by a small number of Pd atoms can exhibit excellent catalytic performance toward the dissociation of H{sub 2} molecule as well as the high selective hydrogenation of acetylene as compared with pure Cu and Pd metal alone at low-temperature, here we performed systematic first-principles calculations to investigate the corresponding reaction mechanism related to the acetylene hydrogenation processes on single atom alloys (SAAs) and monolayer Pd/Cu(111) (i.e.,1.00 ML Pd/Cu(111)) model catalysts in detail, and to explore the possible factors controlling the high selectivity on SAAs. Our results clearly demonstrate that the SAA catalyst has higher selectivity for the ethylene formation than that of 1.00 ML Pd/Cu(111), and lower activity for the acetylene conversion compared with that of 1.00 ML Pd/Cu(111). The relatively high selectivity on SAA is mainly due to the facile desorption of ethylene and moderate activity in the dissociation of molecular H{sub 2}. The main factor which lowers the selectivity towards the ethylene formation on 1.00 ML Pd/Cu(111) is that this system has a higher capacity to promote the breaking of C−H/C−C bonds, which leads to the formation of carbonaceous deposits and polymers such as benzene, and thus reduces the selectivity for the ethylene formation. Meanwhile, it was found that the desorption energy of ethylene on these two surfaces was smaller than the energy barrier of further hydrogenation, which results in the absence of ethane on these two systems. Micro-kinetic model analysis provides a further valuable insight into the evidence for the key factors controlling the catalytic activity and selectivity towards the selective hydrogenation of acetylene. Our findings may help people to design a highly selective hydrogenation catalyst by controlling the balance between the H{sub 2

Water-compatible 'aspartame'-imprinted polymer grafted on silica surface for selective recognition in aqueous solution.

Science.gov (United States)

Singh, Meenakshi; Kumar, Abhishek; Tarannum, Nazia

2013-05-01

Molecularly imprinted polymers selective for aspartame have been prepared using N-[2-ammonium-ethyl-piperazinium) maleimidopropane sulfonate copolymer bearing zwitterionic centres along the backbone via a surface-confined grafting procedure. Aspartame, a dipeptide, is commonly used as an artificial sweetener. Polymerisation on the surface was propagated by means of Michael addition reaction on amino-grafted silica surface. Electrostatic interactions along with complementary H-bonding and other hydrophobic interactions inducing additional synergetic effect between the template (aspartame) and the imprinted surface led to the formation of imprinted sites. The MIP was able to selectively and specifically take up aspartame from aqueous solution and certain pharmaceutical samples quantitatively. Hence, a facile, specific and selective technique using surface-grafted specific molecular contours developed for specific and selective uptake of aspartame in the presence of various interferrants, in different kinds of matrices is presented.

RF plasma based selective modification of hydrophilic regions on super hydrophobic surface

Energy Technology Data Exchange (ETDEWEB)

Lee, Jaehyun; Hwang, Sangyeon; Cho, Dae-Hyun [Department of Mechanical Engineering, Sungkyunkwan University, Suwon 16419 (Korea, Republic of); Hong, Jungwoo [Department of Mechanical Engineering, Graduate of Medical Science and Engineering, Korea Advanced Institute of Science and Technology, Daejeon 34141 (Korea, Republic of); Shin, Jennifer H., E-mail: j_shin@kaist.ac.kr [Department of Mechanical Engineering, Graduate of Medical Science and Engineering, Korea Advanced Institute of Science and Technology, Daejeon 34141 (Korea, Republic of); Byun, Doyoung, E-mail: dybyun@skku.edu [Department of Mechanical Engineering, Sungkyunkwan University, Suwon 16419 (Korea, Republic of)

2017-02-01

Highlights: • Simple and amenable reforming method for a substrate with disparate patterns of hydrophilic dots on super-hydrophobic surfaces is proposed. • Wettability characteristics and modification mechanism for the surfaces are conducted and revealed through SEM, AFM, WSI, and SIMS. • Several representative materials for various applications are successfully deposited. - Abstract: Selective modification and regional alterations of the surface property have gained a great deal of attention to many engineers. In this paper, we present a simple, a cost-effective, and amendable reforming method for disparate patterns of hydrophilic regions on super-hydrophobic surfaces. Uniform super-hydrophobic layer (Contact angle; CA > 150°, root mean square (RMS) roughness ∼0.28 nm) can be formed using the atmospheric radio frequency (RF) plasma on top of the selective hydrophilic (CA ∼ 70°, RMS roughness ∼0.34 nm) patterns imprinted by electrohydrodynamic (EHD) jet printing technology with polar alcohols (butyl carbitol or ethanol). The wettability of the modified surface was investigated qualitatively utilizing scanning electron microscopy (SEM), atomic force microscopy (AFM), and wavelength scanning interferometer (WSI). Secondary ion mass spectroscopy (SIMS) analysis showed that the alcohol addiction reaction changed the types of radicals on the super-hydrophobic surface. The wettability was found to depend sensitively on chemical radicals on the surface, not on surface morphology (particle size and surface roughness). Furthermore, three different kinds of representative hydrophilic samples (polystyrene nano-particle aqueous solution, Salmonella bacteria medium, and poly(3,4-ethylenediocythiophene) ink) were tested for uniform deposition onto the desired hydrophilic regions. This simple strategy would have broad applications in various research fields that require selective deposition of target materials.

RF plasma based selective modification of hydrophilic regions on super hydrophobic surface

International Nuclear Information System (INIS)

Lee, Jaehyun; Hwang, Sangyeon; Cho, Dae-Hyun; Hong, Jungwoo; Shin, Jennifer H.; Byun, Doyoung

2017-01-01

Highlights: • Simple and amenable reforming method for a substrate with disparate patterns of hydrophilic dots on super-hydrophobic surfaces is proposed. • Wettability characteristics and modification mechanism for the surfaces are conducted and revealed through SEM, AFM, WSI, and SIMS. • Several representative materials for various applications are successfully deposited. - Abstract: Selective modification and regional alterations of the surface property have gained a great deal of attention to many engineers. In this paper, we present a simple, a cost-effective, and amendable reforming method for disparate patterns of hydrophilic regions on super-hydrophobic surfaces. Uniform super-hydrophobic layer (Contact angle; CA > 150°, root mean square (RMS) roughness ∼0.28 nm) can be formed using the atmospheric radio frequency (RF) plasma on top of the selective hydrophilic (CA ∼ 70°, RMS roughness ∼0.34 nm) patterns imprinted by electrohydrodynamic (EHD) jet printing technology with polar alcohols (butyl carbitol or ethanol). The wettability of the modified surface was investigated qualitatively utilizing scanning electron microscopy (SEM), atomic force microscopy (AFM), and wavelength scanning interferometer (WSI). Secondary ion mass spectroscopy (SIMS) analysis showed that the alcohol addiction reaction changed the types of radicals on the super-hydrophobic surface. The wettability was found to depend sensitively on chemical radicals on the surface, not on surface morphology (particle size and surface roughness). Furthermore, three different kinds of representative hydrophilic samples (polystyrene nano-particle aqueous solution, Salmonella bacteria medium, and poly(3,4-ethylenediocythiophene) ink) were tested for uniform deposition onto the desired hydrophilic regions. This simple strategy would have broad applications in various research fields that require selective deposition of target materials.

Engineering Cu surfaces for the electrocatalytic conversion of CO2: Controlling selectivity toward oxygenates and hydrocarbons

Science.gov (United States)

Hahn, Christopher; Hatsukade, Toru; Kim, Youn-Geun; Vailionis, Arturas; Baricuatro, Jack H.; Higgins, Drew C.; Nitopi, Stephanie A.; Soriaga, Manuel P.; Jaramillo, Thomas F.

2017-01-01

In this study we control the surface structure of Cu thin-film catalysts to probe the relationship between active sites and catalytic activity for the electroreduction of CO2 to fuels and chemicals. Here, we report physical vapor deposition of Cu thin films on large-format (∼6 cm2) single-crystal substrates, and confirm epitaxial growth in the , , and orientations using X-ray pole figures. To understand the relationship between the bulk and surface structures, in situ electrochemical scanning tunneling microscopy was conducted on Cu(100), (111), and (751) thin films. The studies revealed that Cu(100) and (111) have surface adlattices that are identical to the bulk structure, and that Cu(751) has a heterogeneous kinked surface with (110) terraces that is closely related to the bulk structure. Electrochemical CO2 reduction testing showed that whereas both Cu(100) and (751) thin films are more active and selective for C–C coupling than Cu(111), Cu(751) is the most selective for >2e− oxygenate formation at low overpotentials. Our results demonstrate that epitaxy can be used to grow single-crystal analogous materials as large-format electrodes that provide insights on controlling electrocatalytic activity and selectivity for this reaction. PMID:28533377

High efficiency GaN-based LEDs using plasma selective treatment of p-GaN surface

Energy Technology Data Exchange (ETDEWEB)

Lee, Young-Bae; Naoi, Yoshiki; Sakai, Shiro [Department of Electrical and Electronic Engineering, University of Tokushima, 2-1 Minami-josanjima, Tokushima 770-8506 (Japan); Takaki, Ryohei; Sato, Hisao [Nitride Semiconductor Co., Ltd., 115-7 Itayajima, Akinokami, Seto-cho, Naruto, Tokushima 771-0360 (Japan)

2003-11-01

We have studied a new method of increasing the extraction efficiency of a GaN-based light-emitting diode (LED) using a plasma surface treatment. In this method, prior to the evaporation of a semitransparent p-metal, the surface of a p-GaN located beneath a p-pad is selectively exposed to a nitrogen plasma in a reactive ion etching (RIE) chamber. The electrical characteristics of the plasma treated p-GaN remarkably changes its resistivity into semi-insulator without any parasitic damage. Since the LEDs with a new method have no light absorption in a p-pad region, a higher optical power can be extracted compared to a conventional LEDs without plasma selective treatment on the p-GaN surface. (copyright 2003 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Analysis and optimisation of vertical surface roughness in micro selective laser melting

International Nuclear Information System (INIS)

Abele, Eberhard; Kniepkamp, Michael

2015-01-01

Surface roughness is a major disadvantage of many additive manufacturing technologies like selective laser melting (SLM) compared to established processes like milling or drilling. With recent advancements the resolution of the SLM process could be increased to layer heights of less than 10 μm leading to a new process called micro selective laser melting (μSLM). The purpose of this paper is to analyze the influence of the μSLM process parameters and exposure strategies on the morphology of vertical surfaces. Contour scanning using varying process parameters was used to increase the surface quality. It is shown that it is possible to achieve average surface roughness of less than 1.7 μm using low scan speeds compared to 8–10 μm without contour scanning. Furthermore it is shown that a contour exposure prior to the core exposure leads to surface defects and thus increased roughness. (paper)

Selective metallization of polymers using laser induced surface activation (LISA)—characterization and optimization of porous surface topography

DEFF Research Database (Denmark)

Zhang, Yang; Hansen, Hans Nørgaard; De Grave, Arnaud

2011-01-01

Laser induced selective activation (LISA) is a molded interconnected devices technique for selective metallization of polymers. On the working piece, only the laser-machined area can be metalized in the subsequent plating. The principle of the technology is introduced. Surface analysis was perfor...

A novel surface imprinted polymer/magnetic hydroxyapatite nanocomposite for selective dibenzothiophene scavenging

Science.gov (United States)

Ali, Hager R.; El-Maghrabi, Heba H.; Zahran, Fouad; Moustafa, Yasser Mohamed

2017-12-01

Highly selective adsorbent for dibenzothiophene (DBT) was successfully designed and prepared. Molecularly imprinted polymer (MIP) and magnetic hydroxyapatite (MHAP) were used as building blocks for the novel nanocomposite adsorbent. MIP/MHAP was synthesized by grafting polymerization and surface molecular imprinting using DBT as a template molecule. The microstructure and morphology of the designed nanoadsorbent were examined via FTIR, SEM and VSM. Specific surface area and pore size distribution were determined by Quantachrome Nova 3200S automated gas sorption apparatus. Additionally, static adsorption experiments, isotherms and selective recognition adsorption studies were carried out. Reversed-phase high performance liquid chromatography (RP-HPLC) was used to determine DBT. The experimental data exhibits excellent adsorption capacity for DBT reaches 247 mg/g within 60 min. Competitive adsorption results proved that MIP/MHAP have a greater affinity towards DBT molecules than benzothiophene analogues. Pseudo-second-order model and the Langmuir isotherm were used to describe the adsorption process.

Selectivity/Specificity Improvement Strategies in Surface-Enhanced Raman Spectroscopy Analysis

Directory of Open Access Journals (Sweden)

Feng Wang

2017-11-01

Full Text Available Surface-enhanced Raman spectroscopy (SERS is a powerful technique for the discrimination, identification, and potential quantification of certain compounds/organisms. However, its real application is challenging due to the multiple interference from the complicated detection matrix. Therefore, selective/specific detection is crucial for the real application of SERS technique. We summarize in this review five selective/specific detection techniques (chemical reaction, antibody, aptamer, molecularly imprinted polymers and microfluidics, which can be applied for the rapid and reliable selective/specific detection when coupled with SERS technique.

Mechanical stress-controlled tunable active frequency-selective surface

Science.gov (United States)

Huang, Bo-Cin; Hong, Jian-Wei; Lo, Cheng-Yao

2017-01-01

This study proposes a tunable active frequency-selective surface (AFSS) realized by mechanically expanding or contracting a split-ring resonator (SRR) array. The proposed AFSS transfers mechanical stress from its elastic substrate to the top of the SRR, thereby achieving electromagnetic (EM) modulation without the need for an additional external power supply, meeting the requirements for the target application: the invisibility cloak. The operating mechanism of the proposed AFSS differs from those of other AFSSs, supporting modulations in arbitrary frequencies in the target range. The proposed stress-controlled or strain-induced EM modulation proves the existence of an identical and linear relationship between the strain gradient and the frequency shift, implying its suitability for other EM modulation ranges and applications.

Surface Estimation, Variable Selection, and the Nonparametric Oracle Property.

Science.gov (United States)

Storlie, Curtis B; Bondell, Howard D; Reich, Brian J; Zhang, Hao Helen

2011-04-01

Variable selection for multivariate nonparametric regression is an important, yet challenging, problem due, in part, to the infinite dimensionality of the function space. An ideal selection procedure should be automatic, stable, easy to use, and have desirable asymptotic properties. In particular, we define a selection procedure to be nonparametric oracle (np-oracle) if it consistently selects the correct subset of predictors and at the same time estimates the smooth surface at the optimal nonparametric rate, as the sample size goes to infinity. In this paper, we propose a model selection procedure for nonparametric models, and explore the conditions under which the new method enjoys the aforementioned properties. Developed in the framework of smoothing spline ANOVA, our estimator is obtained via solving a regularization problem with a novel adaptive penalty on the sum of functional component norms. Theoretical properties of the new estimator are established. Additionally, numerous simulated and real examples further demonstrate that the new approach substantially outperforms other existing methods in the finite sample setting.

Bridging the Gap: From Model Surfaces to Nanoparticle Analogs for Selective Oxidation and Steam Reforming of Methanol and Selective Hydrogenation Catalysis

Science.gov (United States)

Boucher, Matthew B.

Most industrial catalysts are very complex, comprising of non-uniform materials with varying structures, impurities, and interaction between the active metal and supporting substrate. A large portion of the ongoing research in heterogeneous catalysis focuses on understanding structure-function relationships in catalytic materials. In parallel, there is a large area of surface science research focused on studying model catalytic systems for which structural parameters can be tuned and measured with high precision. It is commonly argued, however, that these systems are oversimplified, and that observations made in model systems do not translate to robust catalysts operating in practical environments; this discontinuity is often referred to as a "gap." The focus of this thesis is to explore the mutual benefits of surface science and catalysis, or "bridge the gap," by studying two catalytic systems in both ultra-high vacuum (UHV) and near ambient-environments. The first reaction is the catalytic steam reforming of methanol (SRM) to hydrogen and carbon dioxide. The SRM reaction is a promising route for on-demand hydrogen production. For this catalytic system, the central hypothesis in this thesis is that a balance between redox capability and weak binding of reaction intermediates is necessary for high SRM activity and selectivity to carbon dioxide. As such, a new catalyst for the SRM reaction is developed which incorporates very small amounts of gold (liquid-phase, stirred-tank batch reactor under a hydrogen head pressure of approximately 7 bar. Palladium alloyed into the surface of otherwise inactive copper nanoparticles shows a marked improvement in selectivity when compared to monometallic palladium catalysts with the same metal loading. This effect is attributed hydrogen spillover onto the copper surface. In summary, the development of new, highly active and selective catalysts for the methanol steam reforming reaction and for the partial hydrogenation of alkynes

Selective scanning tunnelling microscope electron-induced reactions of single biphenyl molecules on a Si(100) surface.

Science.gov (United States)

Riedel, Damien; Bocquet, Marie-Laure; Lesnard, Hervé; Lastapis, Mathieu; Lorente, Nicolas; Sonnet, Philippe; Dujardin, Gérald

2009-06-03

Selective electron-induced reactions of individual biphenyl molecules adsorbed in their weakly chemisorbed configuration on a Si(100) surface are investigated by using the tip of a low-temperature (5 K) scanning tunnelling microscope (STM) as an atomic size source of electrons. Selected types of molecular reactions are produced, depending on the polarity of the surface voltage during STM excitation. At negative surface voltages, the biphenyl molecule diffuses across the surface in its weakly chemisorbed configuration. At positive surface voltages, different types of molecular reactions are activated, which involve the change of adsorption configuration from the weakly chemisorbed to the strongly chemisorbed bistable and quadristable configurations. Calculated reaction pathways of the molecular reactions on the silicon surface, using the nudge elastic band method, provide evidence that the observed selectivity as a function of the surface voltage polarity cannot be ascribed to different activation energies. These results, together with the measured threshold surface voltages and the calculated molecular electronic structures via density functional theory, suggest that the electron-induced molecular reactions are driven by selective electron detachment (oxidation) or attachment (reduction) processes.

The Study of Selected Properties of Ti EB PVD Coating Deposited Onto Inner Tube Surface at Low Temperature

Directory of Open Access Journals (Sweden)

Kottfer D.

2016-03-01

Full Text Available This study investigates the selected properties of the thin Ti coating applied by activated evaporation EB PVD technique. This technique was used for the deposition of Ti thin coating onto inner surface of OKhN3 MFA steel tubes. Deposition process was carried out at temperature 200°C. Conventional type of coatings - monolayer Ti - was analyzed by standard techniques for surface status and quality assessment - coating thickness, chemical composition by EDX analysis, adhesion, hardness, roughness, and growth direction of columns at room temperature. Ti monolayer achieved roughness Ra equal from 0.42 μm to 0.47 μm. The resulting hardness was from 2 GPa to 8.5 GPa depending on the sample location inside the vacuum chamber. Placing of the coated surface also affected the direction of grain growth of Ti coating columns. The angles α of grain growth were found to be from 40° to 60°. Angle α increased two to three times more than the incidence angle β (from 12° to 28° of evaporated Ti particles. Values of the adhesion measured along the Ti growth direction were mostly higher (up to 10% or the same as those measured perpendicular to it.

Surface-Selective Preferential Production of Reactive Oxygen Species on Piezoelectric Ceramics for Bacterial Killing.

Science.gov (United States)

Tan, Guoxin; Wang, Shuangying; Zhu, Ye; Zhou, Lei; Yu, Peng; Wang, Xiaolan; He, Tianrui; Chen, Junqi; Mao, Chuanbin; Ning, Chengyun

2016-09-21

Reactive oxygen species (ROS) can be used to kill bacterial cells, and thus the selective generation of ROS from material surfaces is an emerging direction in antibacterial material discovery. We found the polarization of piezoelectric ceramic causes the two sides of the disk to become positively and negatively charged, which translate into cathode and anode surfaces in an aqueous solution. Because of the microelectrolysis of water, ROS are preferentially formed on the cathode surface. Consequently, the bacteria are selectively killed on the cathode surface. However, the cell experiment suggested that the level of ROS is safe for normal mammalian cells.

Frequency Selective Surfaces for extended Bandwidth backing reflector functions

NARCIS (Netherlands)

Pasian, M.; Neto, A.; Monni, S.; Ettorre, M.; Gerini, G.

2008-01-01

This paper deals with the use of Frequency Selective Surfaces (FSS) to increase the Efficiency × Bandwidth product in Ultra-Wide Band (UWB) antenna arrays whose efficiency is limited by the front-to-back ratio. If the backing reflector is realized in one metal plane solution its location will be

Surface-imprinted core–shell Au nanoparticles for selective detection of bisphenol A based on surface-enhanced Raman scattering

International Nuclear Information System (INIS)

Xue, Jin-Qun; Li, Da-Wei; Qu, Lu-Lu; Long, Yi-Tao

2013-01-01

Graphical abstract: -- Highlights: •The molecularly imprinted polymer capped core–shell AuNPs (MIP-ir-AuNPs) were fabricated as a specific functional SERS substrate. •MIP-ir-AuNPs could be utilized in rapid and selective detection of BPA. •MIP-ir-AuNPs displayed good capability for determination of BPA in real samples. -- Abstract: Surface-imprinted core–shell Au nanoparticles (AuNPs) were explored for the highly selective detection of bisphenol A (BPA) by surface-enhanced Raman scattering (SERS). A triethoxysilane-template complex (BPA-Si) was synthesized and then utilized to fabricate a molecularly imprinted polymer (MIP) layer on the AuNPs via a sol–gel process. The imprinted BPA molecules were removed by a simple thermal treatment to generated the imprint-removed material, MIP-ir-AuNPs, with the desired recognition sites that could selectively rebind the BPA molecules. The morphological and polymeric characteristics of MIP-ir-AuNPs were investigated by transmission electron microscopy and Fourier-transform infrared spectroscopy. The results demonstrated that the MIP-ir-AuNPs were fabricated with a 2 nm MIP shell layer within which abundant amine groups were generated. The rebinding kinetics study showed that the MIP-ir-AuNPs could reach the equilibrium adsorption for BPA within 10 min owning to the advantage of ultrathin core–shell nanostructure. Moreover, a linear relationship between SERS intensity and the concentration of BPA on the MIP-ir-AuNPs was observed in the range of 0.5–22.8 mg L −1 , with a detection limit of 0.12 mg L −1 (blank ± 3 × s.d.). When applied to SERS detection, the developed surface-imprinted core–shell MIP-ir-AuNPs could recognize BPA and prevent interference from the structural analogues such as hexafluorobisphenol A (BPAF) and diethylstilbestrol (DES). These results revealed that the proposed method displayed significant potential utility in rapid and selective detection of BPA in real samples

The effect of selected parameters of the honing process on cylinder liner surface topography

International Nuclear Information System (INIS)

Pawlus, P; Dzierwa, A; Michalski, J; Reizer, R; Wieczorowski, M; Majchrowski, R

2014-01-01

Many truck cylinder liners made from gray cast iron were machined. Ceramic and diamond honing stones were used in the last stages of operation: coarse honing and plateau honing. The effect of honing parameters on the cylinder liner surface topography was studied. Selected surface topography parameters were response variables. It was found that parameters from the Sq group were sensitive to honing parameter change. When plateau honing time varied, the Smq parameter increased, while the other parameters, Spq and Svq, were stable. (papers)

Plastic antibody based surface plasmon resonance nanosensors for selective atrazine detection

Energy Technology Data Exchange (ETDEWEB)

Yılmaz, Erkut [Department of Chemistry, Aksaray University, 68100 Aksaray (Turkey); Özgür, Erdoğan; Bereli, Nilay; Türkmen, Deniz [Department of Chemistry, Hacettepe University, 06800 Ankara (Turkey); Denizli, Adil, E-mail: denizli@hacettepe.edu.tr [Department of Chemistry, Hacettepe University, 06800 Ankara (Turkey)

2017-04-01

This study reports a surface plasmon resonance (SPR) based affinity sensor system with the use of molecular imprinted nanoparticles (plastic antibodies) to enhance the pesticide detection. Molecular imprinting based affinity sensor is prepared by the attachment of atrazine (chosen as model pesticide) imprinted nanoparticles onto the gold surface of SPR chip. Recognition element of the affinity sensor is polymerizable form of aspartic acid. The imprinted nanoparticles were characterized via FTIR and zeta-sizer measurements. SPR sensors are characterized with atomic force microscopy (AFM), scanning electron microscopy (SEM), Fourier transform infrared spectrophotometry (FTIR) and contact angle measurements. The imprinted nanoparticles showed more sensitivity to atrazine than the non-imprinted ones. Different concentrations of atrazine solutions are applied to SPR system to determine the adsorption kinetics. Langmuir adsorption model is found as the most suitable model for this affinity nanosensor system. In order to show the selectivity of the atrazine-imprinted nanoparticles, competitive adsorption of atrazine, simazine and amitrole is investigated. The results showed that the imprinted nanosensor has high selectivity and sensitivity for atrazine. - Highlights: • SPR based affinity sensor system was developed via molecular imprinting. • Recognition element of the affinity sensor is polymerizable form of an amino acid. • Combination of SPR and MIP offers highly selective sensor with long shelf-life. • Plastic antibody based biomimetic sensors offer relatively cheaper production. • Plastic antibody based biomimetic sensors offer high physical, chemical stability.

Plastic antibody based surface plasmon resonance nanosensors for selective atrazine detection

International Nuclear Information System (INIS)

Yılmaz, Erkut; Özgür, Erdoğan; Bereli, Nilay; Türkmen, Deniz; Denizli, Adil

2017-01-01

This study reports a surface plasmon resonance (SPR) based affinity sensor system with the use of molecular imprinted nanoparticles (plastic antibodies) to enhance the pesticide detection. Molecular imprinting based affinity sensor is prepared by the attachment of atrazine (chosen as model pesticide) imprinted nanoparticles onto the gold surface of SPR chip. Recognition element of the affinity sensor is polymerizable form of aspartic acid. The imprinted nanoparticles were characterized via FTIR and zeta-sizer measurements. SPR sensors are characterized with atomic force microscopy (AFM), scanning electron microscopy (SEM), Fourier transform infrared spectrophotometry (FTIR) and contact angle measurements. The imprinted nanoparticles showed more sensitivity to atrazine than the non-imprinted ones. Different concentrations of atrazine solutions are applied to SPR system to determine the adsorption kinetics. Langmuir adsorption model is found as the most suitable model for this affinity nanosensor system. In order to show the selectivity of the atrazine-imprinted nanoparticles, competitive adsorption of atrazine, simazine and amitrole is investigated. The results showed that the imprinted nanosensor has high selectivity and sensitivity for atrazine. - Highlights: • SPR based affinity sensor system was developed via molecular imprinting. • Recognition element of the affinity sensor is polymerizable form of an amino acid. • Combination of SPR and MIP offers highly selective sensor with long shelf-life. • Plastic antibody based biomimetic sensors offer relatively cheaper production. • Plastic antibody based biomimetic sensors offer high physical, chemical stability.

Frequency-Wavenumber (FK)-Based Data Selection in High-Frequency Passive Surface Wave Survey

Science.gov (United States)

Cheng, Feng; Xia, Jianghai; Xu, Zongbo; Hu, Yue; Mi, Binbin

2018-04-01

Passive surface wave methods have gained much attention from geophysical and civil engineering communities because of the limited application of traditional seismic surveys in highly populated urban areas. Considering that they can provide high-frequency phase velocity information up to several tens of Hz, the active surface wave survey would be omitted and the amount of field work could be dramatically reduced. However, the measured dispersion energy image in the passive surface wave survey would usually be polluted by a type of "crossed" artifacts at high frequencies. It is common in the bidirectional noise distribution case with a linear receiver array deployed along roads or railways. We review several frequently used passive surface wave methods and derive the underlying physics for the existence of the "crossed" artifacts. We prove that the "crossed" artifacts would cross the true surface wave energy at fixed points in the f-v domain and propose a FK-based data selection technique to attenuate the artifacts in order to retrieve the high-frequency information. Numerical tests further demonstrate the existence of the "crossed" artifacts and indicate that the well-known wave field separation method, FK filter, does not work for the selection of directional noise data. Real-world applications manifest the feasibility of the proposed FK-based technique to improve passive surface wave methods by a priori data selection. Finally, we discuss the applicability of our approach.

Frequency-Wavenumber (FK)-Based Data Selection in High-Frequency Passive Surface Wave Survey

Science.gov (United States)

Cheng, Feng; Xia, Jianghai; Xu, Zongbo; Hu, Yue; Mi, Binbin

2018-07-01

Passive surface wave methods have gained much attention from geophysical and civil engineering communities because of the limited application of traditional seismic surveys in highly populated urban areas. Considering that they can provide high-frequency phase velocity information up to several tens of Hz, the active surface wave survey would be omitted and the amount of field work could be dramatically reduced. However, the measured dispersion energy image in the passive surface wave survey would usually be polluted by a type of "crossed" artifacts at high frequencies. It is common in the bidirectional noise distribution case with a linear receiver array deployed along roads or railways. We review several frequently used passive surface wave methods and derive the underlying physics for the existence of the "crossed" artifacts. We prove that the "crossed" artifacts would cross the true surface wave energy at fixed points in the f- v domain and propose a FK-based data selection technique to attenuate the artifacts in order to retrieve the high-frequency information. Numerical tests further demonstrate the existence of the "crossed" artifacts and indicate that the well-known wave field separation method, FK filter, does not work for the selection of directional noise data. Real-world applications manifest the feasibility of the proposed FK-based technique to improve passive surface wave methods by a priori data selection. Finally, we discuss the applicability of our approach.

Surface chemistry of Ti6Al4V components fabricated using selective laser melting for biomedical applications

Energy Technology Data Exchange (ETDEWEB)

Vaithilingam, Jayasheelan, E-mail: Jayasheelan.Vaithilingam@nottingham.ac.uk [Additive Manufacturing and 3D Printing Research Group, EPSRC Centre for Innovative Manufacturing in Additive Manufacturing, School of Engineering, The University of Nottingham, Nottingham NG7 2RD (United Kingdom); Prina, Elisabetta [School of Pharmacy, Centre for Biomolecular Sciences, The University of Nottingham, Nottingham NG7 2RD (United Kingdom); Goodridge, Ruth D.; Hague, Richard J.M. [Additive Manufacturing and 3D Printing Research Group, EPSRC Centre for Innovative Manufacturing in Additive Manufacturing, School of Engineering, The University of Nottingham, Nottingham NG7 2RD (United Kingdom); Edmondson, Steve [School of Materials, The University of Manchester, Manchester M13 9PL (United Kingdom); Rose, Felicity R.A.J. [School of Pharmacy, Centre for Biomolecular Sciences, The University of Nottingham, Nottingham NG7 2RD (United Kingdom); Christie, Steven D.R. [Department of Chemistry, Loughborough University, Loughborough LE11 3TU (United Kingdom)

2016-10-01

Selective laser melting (SLM) has previously been shown to be a viable method for fabricating biomedical implants; however, the surface chemistry of SLM fabricated parts is poorly understood. In this study, X-ray photoelectron spectroscopy (XPS) was used to determine the surface chemistries of (a) SLM as-fabricated (SLM-AF) Ti6Al4V and (b) SLM fabricated and mechanically polished (SLM-MP) Ti6Al4V samples and compared with (c) traditionally manufactured (forged) and mechanically polished Ti6Al4V samples. The SLM–AF surface was observed to be porous with an average surface roughness (Ra) of 17.6 ± 3.7 μm. The surface chemistry of the SLM-AF was significantly different to the FGD-MP surface with respect to elemental distribution and their existence on the outermost surface. Sintered particles on the SLM-AF surface were observed to affect depth profiling of the sample due to a shadowing effect during argon ion sputtering. Surface heterogeneity was observed for all three surfaces; however, vanadium was witnessed only on the mechanically polished (SLM-MP and FGD-MP) surfaces. The direct and indirect 3T3 cell cytotoxicity studies revealed that the cells were viable on the SLM fabricated Ti6Al4V parts. The varied surface chemistry of the SLM-AF and SLM-MP did not influence the cell behaviour. - Highlights: • Surface chemistry of selective laser melted (SLM) Ti6Al4V parts was compared with conventionally forged Ti6Al4V parts. • The surface elemental compositions of the SLM as-fabricated surfaces were significantly different to the forged surface. • Surface oxide-layer of the SLM as-fabricated was thicker than the polished SLM surfaces and the forged Ti6Al4V surfaces.

A Highly Selective Sensor for Cyanide in Organic Media and on Solid Surfaces

Directory of Open Access Journals (Sweden)

Belygona Barare

2016-02-01

Full Text Available The application of IR 786 perchlorate (IR-786 as a selective optical sensor for cyanide anion in both organic solution (acetonitrile (MeCN, 100% and solvent-free solid surfaces was demonstrated. In MeCN, IR-786 was selective to two anions in the following order: CN− > OH−. A significant change in the characteristic dark green color of IR-786 in MeCN to yellow was observed as a result of nucleophilic addition of CN− to the fluorophore, i.e., formation of IR 786-(CN, which was also verified by a blue shift in the 775 nm absorbance peak to 430 nm. A distinct green fluorescence emission from the IR-786-(CN in MeCN was also observed, which demonstrated the selectivity of IR-786 towards CN− in MeCN. Fluorescence emission studies of IR-786 showed that the lower detection limit and the sensitivity of IR-786 for CN− in MeCN was 0.5 μM and 0.5 to 8 μM, respectively. The potential use of IR-786 as a solvent-free solid state sensor for the selective sensing and monitoring of CN− in the environment was also demonstrated. On solvent-free solid state surfaces, the sensitivity of the IR-786 to CN− in water samples was in the range of 50–300 μM with minimal interference by OH−.

Controlling hydrogenation activity and selectivity of bimetallic surfaces and catalysts

Science.gov (United States)

Murillo, Luis E.

also discussed. Chemisorption, TPD, FTIR using a batch reactor for the self-hydrogenation of cyclohexene and CO adsorbed on the bimetallic surfaces were carried out to correlate surface science findings with experiments on supported bimetallic catalysts. To expand the studies on the effect of bimetallic structures on hydrogenation reactions, molecules with multiple functional groups such as alpha,beta-unsaturated aldehydes were also investigated. Studies of selective hydrogenation of a,ss-unsaturated aldehydes toward the desired unsaturated alcohols are of interest for the production of fine chemicals and pharmaceuticals. In these compounds, competitive hydrogenation of the C=C and C=O bonds occurs. TPD and HREELS experiments of acrolein (CH2=CH-CH=O) on Pt-based bimetallic surfaces are performed to investigate their effects on the hydrogenation activity of the C-O bond. The production of the desired unsaturated alcohol, allyl alcohol, has been observed for the first time on Pt-Ni-Pt(111) under UHV conditions. However, the propionaldehyde yield is five times higher than the allyl alcohol yield. Thus, a preferential isomerization reaction of allyl alcohol to propionaldehyde is very likely to occur on the Pt-Ni-Pt(111) surface as observed on the desorption studies of allyl alcohol on this surface. The hydrogenation of acrolein is also carried out under UHV conditions on other 3d-transition metal/Pt(111) surfaces such as Co/Pt(111), Fe/Pt(111), and Cu/Pt(111). So far, the highest activity and allyl alcohol yield are found on the Pt-Ni-Pt(111) surface with pre-adsorbed hydrogen.

Effect of Build Angle on Surface Properties of Nickel Superalloys Processed by Selective Laser Melting

Science.gov (United States)

Covarrubias, Ernesto E.; Eshraghi, Mohsen

2018-03-01

Aerospace, automotive, and medical industries use selective laser melting (SLM) to produce complex parts through solidifying successive layers of powder. This additive manufacturing technique has many advantages, but one of the biggest challenges facing this process is the resulting surface quality of the as-built parts. The purpose of this research was to study the surface properties of Inconel 718 alloys fabricated by SLM. The effect of build angle on the surface properties of as-built parts was investigated. Two sets of sample geometries including cube and rectangular artifacts were considered in the study. It was found that, for angles between 15° and 75°, theoretical calculations based on the "stair-step" effect were consistent with the experimental results. Downskin surfaces showed higher average roughness values compared to the upskin surfaces. No significant difference was found between the average roughness values measured from cube and rectangular test artifacts.

Study of surface modifications for improved selected metal (II-VI) semiconductor based devices

Science.gov (United States)

Blomfield, Christopher James

Metal-semiconductor contacts are of fundamental importance to the operation of all semiconductor devices. There are many competing theories of Schottky barrier formation but as yet no quantitative predictive model exists to adequately explain metal-semiconductor interfaces. The II-VI compound semiconductors CdTe, CdS and ZnSe have recently come to the fore with the advent of high efficiency photovoltaic cells and short wavelength light emitters. Major problems still exist however in forming metal contacts to these materials with the desired properties. This work presents results which make a significant contribution to the theory of metal/II-VI interface behaviour in terms of Schottky barriers to n-type CdTe, CdS and ZnSe.Predominantly aqueous based wet chemical etchants were applied to the surfaces of CdTe, CdS and ZnSe which were subsequently characterised by X-ray photoelectron spectroscopy. The ionic nature of these II-VI compounds meant that they behaved as insoluble salts of strong bases and weak acids. Acid etchants induced a stoichiometric excess of semiconductor anion at the surface which appeared to be predominantly in the elemental or hydrogenated state. Alkaline etchants conversely induced a stoichiometric excess of semiconductor cation at the surface which appeared to be in an oxidised state.Metal contacts were vacuum-evaporated onto these etched surfaces and characterised by current-voltage and capacitance-voltage techniques. The surface preparation was found to have a clear influence upon the electrical properties of Schottky barriers formed to etched surfaces. Reducing the native surface oxide produced near ideal Schottky diodes. An extended study of Au, Ag and Sb contacts to [mathematical formula] substrates again revealed the formation of several discrete Schottky barriers largely independent of the metal used; for [mathematical formula]. Deep levels measured within this study and those reported in the literature led to the conclusion that Fermi

Experimental Comparison of the Tribological Properties of Selected Surfaces Created by Thermal Spraying Technology

Directory of Open Access Journals (Sweden)

František Tóth

2016-01-01

Full Text Available The scientific article titled “Experimental comparison of the tribological properties of selected surfaces created by thermal spraying technology” deals with the surface condition of selected pairs working within the mixed friction before and after experimental tests. Based on the chosen methodology, the experimental tests were performed on the Tribotestor M’06 testing machine. The ecological oil MOGUL HEES 46 (manufactured by Paramo was used as a lubricant. The tests were performed on selected material pairs. The first friction element was a shaft of steel 14 220. The second friction element was a steel plate of steel 11 373 with a friction surface created by two materials, i.e. CuSn10 and NP 40. The results are statistically elaborated and illustrated in figures and tables.

Selective cell-surface labeling of the molecular motor protein prestin

International Nuclear Information System (INIS)

McGuire, Ryan M.; Silberg, Jonathan J.; Pereira, Fred A.; Raphael, Robert M.

2011-01-01

Highlights: → Trafficking to the plasma membrane is required for prestin function. → Biotin acceptor peptide (BAP) was fused to prestin through a transmembrane domain. → BAP-prestin can be metabolically labeled with biotin in HEK293 cells. → Biotin-BAP-prestin allows for selective imaging of fully trafficked prestin. → The biotin-BAP-prestin displays voltage-sensitive activity. -- Abstract: Prestin, a multipass transmembrane protein whose N- and C-termini are localized to the cytoplasm, must be trafficked to the plasma membrane to fulfill its cellular function as a molecular motor. One challenge in studying prestin sequence-function relationships within living cells is separating the effects of amino acid substitutions on prestin trafficking, plasma membrane localization and function. To develop an approach for directly assessing prestin levels at the plasma membrane, we have investigated whether fusion of prestin to a single pass transmembrane protein results in a functional fusion protein with a surface-exposed N-terminal tag that can be detected in living cells. We find that fusion of the biotin-acceptor peptide (BAP) and transmembrane domain of the platelet-derived growth factor receptor (PDGFR) to the N-terminus of prestin-GFP yields a membrane protein that can be metabolically-labeled with biotin, trafficked to the plasma membrane, and selectively detected at the plasma membrane using fluorescently-tagged streptavidin. Furthermore, we show that the addition of a surface detectable tag and a single-pass transmembrane domain to prestin does not disrupt its voltage-sensitive activity.

Selected anionic and cationic surface active agents: case study on the Kłodnica sediments

Directory of Open Access Journals (Sweden)

Olkowska Ewa

2017-03-01

Full Text Available Surface active agents (surfactants are a group of chemical compounds, which are used as ingredients of detergents, cleaning products, cosmetics and functional products. After use, wastes containing surfactants or their degradation products are discharged to wastewater treatment plants or directly into surface waters. Due to their specific properties of SAAs, compounds are able to migrate between different environmental compartments such as soil, sediment, water or even living organisms and accumulate there. Surfactants can have a harmful effect on living organisms. They can connect with bioactive molecules and modify their function. Additionally, they have the ability to migrate into cells and cause their damage or death. For these reasons investigation of individual surfactants should be conducted. The presented research has been undertaken to obtain information about SAA contamination of sediment from the River Kłodnica catchment caused by selected anionic (linear alkylbenzene sulfonates (LAS C10-C13 and cationic (alkylbenzyldimethylammonium (BDMA-C12-16, alkyl trimethyl ammonium (DTMA, hexadecyl piridinium chloride (HP chlorides surfactants. This river flows through an area of the Upper Silesia Industrial Region where various companies and other institutions (e.g. coal mining, power plants, metallurgy, hospitals are located. To determine their concentration the following analytical tools have been applied: accelerated solvent extraction– solid phase extraction – high performance liquid chromatography – UV-Vis (anionic SAAs and conductivity (cationic SAAs detectors. In all sediments anionic SAAs have been detected. The concentrations of HTMA and BDMA-C16 in tested samples were higher than other cationic analytes. Generally, levels of surfactants with longer alkyl chains were higher and this observation can confirm their higher susceptibility to sorption on solid surfaces.

Corrosion protection of PVD and paint coatings for selective solar absorber surfaces

OpenAIRE

Nunes, A.; Carvalho, M. J.; Diamantino, Teresa C.; Fernandes, J. C. S.

2015-01-01

The selective solar absorber surface is a fundamental part of a solar thermal collector, as it is responsible for the solar radiation absorption and for reduction of radiation heat losses. The surface’s optical properties, the solar absorption (á) and the emittance (å), have great impact on the solar thermal collector efficiency. In this work, two coatings types were studied: coatings obtained by physical vapor deposition (PVDs) and coatings obtained by projection with different paints (PCs) ...

Surface properties and corrosion behavior of Co-Cr alloy fabricated with selective laser melting technique.

Science.gov (United States)

Xin, Xian-zhen; Chen, Jie; Xiang, Nan; Wei, Bin

2013-01-01

We sought to study the corrosion behavior and surface properties of a commercial cobalt-chromium (Co-Cr) alloy which was fabricated with selective laser melting (SLM) technique. For this purpose, specimens were fabricated using different techniques, such as SLM system and casting methods. Surface hardness testing, microstructure observation, surface analysis using X-ray photoelectron spectroscopy (XPS) and electrochemical corrosion test were carried out to evaluate the corrosion properties and surface properties of the specimens. We found that microstructure of SLM specimens was more homogeneous than that of cast specimens. The mean surface hardness values of SLM and cast specimens were 458.3 and 384.8, respectively; SLM specimens showed higher values than cast ones in hardness. Both specimens exhibited no differences in their electrochemical corrosion properties in the artificial saliva through potentiodynamic curves and EIS, and no significant difference via XPS. Therefore, we concluded that within the scope of this study, SLM-fabricated restorations revealed good surface properties, such as proper hardness, homogeneous microstructure, and also showed sufficient corrosion resistance which could meet the needs of dental clinics.

Quantum trajectories in elastic atom-surface scattering: threshold and selective adsorption resonances.

Science.gov (United States)

Sanz, A S; Miret-Artés, S

2005-01-01

The elastic resonant scattering of He atoms off the Cu(117) surface is fully described with the formalism of quantum trajectories provided by Bohmian mechanics. Within this theory of quantum motion, the concept of trapping is widely studied and discussed. Classically, atoms undergo impulsive collisions with the surface, and then the trapped motion takes place covering at least two consecutive unit cells. However, from a Bohmian viewpoint, atom trajectories can smoothly adjust to the equipotential energy surface profile in a sort of sliding motion; thus the trapping process could eventually occur within one single unit cell. In particular, both threshold and selective adsorption resonances are explained by means of this quantum trapping considering different space and time scales. Furthermore, a mapping between each region of the (initial) incoming plane wave and the different parts of the diffraction and resonance patterns can be easily established, an important issue only provided by a quantum trajectory formalism. (c) 2005 American Institute of Physics.

Pathway and Surface Mechanism Studies of 1,3-butadiene Selective Oxidation Over Vanadium-Molybdenum-Oxygen Catalysts

Energy Technology Data Exchange (ETDEWEB)

Schroeder, William David [Iowa State Univ., Ames, IA (United States)

2001-01-01

The partial oxidation of 1,3-butadiene has been investigated over VMoO catalysts synthesized by sol-gel techniques. Surface areas were 9-14 m²/g, and compositions were within the solid solution regime, i.e. below 15.0 mol % MoO₃/(MoO₃ + V₂O₅). Laser Raman Spectroscopy and XRD data indicated that solid solutions were formed, and pre- and post-reaction XPS data indicated that catalyst surfaces contained some V⁺⁴ and were further reduced in 1,3-butadiene oxidation. A reaction pathway for 1,3-butadiene partial oxidation to maleic anhydride was shown to involve intermediates such as 3,4-epoxy-1-butene, crotonaldehyde, furan, and 2-butene-1,4-dial. The addition of water to the reaction stream substantially increased catalyst activity and improved selectivity to crotonaldehyde and furan at specific reaction temperatures. At higher water addition concentrations, furan selectivity increased from 12% to over 25%. The catalytic effects of water addition were related to competitive adsorption with various V₂O₅-based surface sites, including the vanadyl V=O, corner sharing V-O-V and edge sharing V-O oxygen. Higher levels of water addition were proposed to impose acidic character by dissociative adsorption. In addition, a novel combinatorial synthesis technique for VMoO was used to investigate the phase transitions of V₂O₅, solid solutions of Mo in V₂O₅, V₉Mo₆O₄₀, and other reduced VMoO compounds, characterized by laser Raman spectroscopy. The natural composition gradient imposed by the sputter deposition apparatus was used to create VMoO arrays containing 225 samples ranging from 7.0-42 mol% MoO₃/(V₂O₅ + MoO₃), determined by EDS analysis.

Selective Binding, Self-Assembly and Nanopatterning of the Creutz-Taube Ion on Surfaces

Directory of Open Access Journals (Sweden)

Qingling Hang

2009-02-01

Full Text Available The surface attachment properties of the Creutz-Taube ion, i.e., [(NH35Ru(pyrazineRu(NH35]5+, on both hydrophilic and hydrophobic types of surfaces were investigated using X-ray photoelectron spectroscopy (XPS. The results indicated that the Creutz-Taube ions only bound to hydrophilic surfaces, such as SiO2 and –OH terminated organic SAMs on gold substrates. No attachment of the ions on hydrophobic surfaces such as –CH3 terminated organic SAMs and poly(methylmethacrylate (PMMA thin films covered gold or SiO2 substrates was observed. Further ellipsometric, atomic force microscopy (AFM and time-dependent XPS studies suggested that the attached cations could form an inorganic analog of the self-assembled monolayer on SiO2 substrate with a “lying-down” orientation. The strong electrostatic interaction between the highly charged cations and the anionic SiO2 surface was believed to account for these observations. Based on its selective binding property, patterning of wide (~200 nm and narrow (~35 nm lines of the Creutz-Taube ions on SiO2 surface were demonstrated through PMMA electron resist masks written by electron beam lithography (EBL.

Selective electrochemical gold deposition onto p-Si (1 0 0) surfaces

Energy Technology Data Exchange (ETDEWEB)

Santinacci, L; Etcheberry, A [Institut Lavoisier de Versailles (UMR CNRS 8180), University of Versailles-Saint-Quentin, 45 avenue des Etats-Unis, F-78035 Versailles cedex (France); Djenizian, T [Laboratoire Chimie Provence (UMR CNRS 6264), University of Aix-Marseille I-II-III, Centre Saint-Jerome, F-13397 Marseille Cedex 20 (France); Schwaller, P [Laboratory for Mechanics of Materials and Nanostructures, Swiss Federal Laboratory for Materials Testing and Research, Feuerwerkstr. 39, CH-3602 Thun (Switzerland); Suter, T [Laboratory for Corrosion and Materials Integrity, Swiss Federal Laboratory for Materials Testing and Research, Ueberlandstr. 129, CH-8600 Duebendorf (Switzerland); Schmuki, P [Department of Materials Science, LKO-WW4, Friedrich-Alexander-University Erlangen-Nuremberg, Martensstr. 7, D-91058 Erlangen (Germany)], E-mail: lionel.santinacci@uvsq.fr

2008-09-07

In this paper, we report selective electrochemical gold deposition onto p-type Si (1 0 0) into nanoscratches produced through a thin oxide layer using an atomic force microscope. A detailed description of the substrate engraving process is presented. The influence of the main scratching parameters such as the normal applied force, the number of scans and the scanning velocity are investigated as well as the mechanical properties of the substrate. Gold deposition is carried out in a KAu(CN){sub 2} + KCN solution by applying cathodic voltages for various durations. The gold deposition process is investigated by cyclic voltammetry. Reactivity enhancement at the scratched locations was studied by comparing the electrochemical behaviour of intact and engraved surfaces using a micro-electrochemical setup. Selective electrochemical gold deposition is achieved: metallic patterns with a sub-500 nm lateral resolution are obtained demonstrating, therefore, the bearing potential of this patterning technique.

Dual brush process for selective surface modification in graphoepitaxy directed self-assembly

Science.gov (United States)

Doise, Jan; Chan, Boon Teik; Hori, Masafumi; Gronheid, Roel

2017-07-01

Graphoepitaxy directed self-assembly is a potential low-cost solution for patterning via layers with pitches beyond the reach of a single optical lithographic exposure. In this process, selective control of the interfacial energy at the bottom and sidewall of the template is an important but challenging exercise. A dual brush process is implemented, in which two brushes with distinct end-groups are consecutively grafted to the prepattern to achieve fully independent modification of the bottom and sidewall surface of the template. A comprehensive study of hole pattern quality shows that using a dual brush process leads to a substantial improvement in terms of positional and dimensional variability across the process window. These findings will be useful to others who wish to manipulate polymer-surface interactions in directed self-assembly flows.

Selective radiolabeling of cell surface proteins to a high specific activity

International Nuclear Information System (INIS)

Thompson, J.A.; Lau, A.L.; Cunningham, D.D.

1987-01-01

A procedure was developed for selective radiolabeling of membrane proteins on cells to higher specific activities than possible with available techniques. Cell surface amino groups were derivatized with 125 I-(hydroxyphenyl)propionyl groups via 125 I-sulfosuccinimidyl (hydroxyphenyl)propionate ( 125 II-sulfo-SHPP). This reagent preferentially labeled membrane proteins exposed at the cell surface of erythrocytes as assessed by the degree of radiolabel incorporation into erythrocyte ghost proteins and hemoglobin. Comparison with the lactoperoxidase-[ 125 I]iodide labeling technique revealed that 125 I-sulfo-SHPP labeled cell surface proteins to a much higher specific activity and hemoglobin to a much lower specific activity. Additionally, this reagent was used for selective radiolabeling of membrane proteins on the cytoplasmic face of the plasma membrane by blocking exofacial amino groups with uniodinated sulfo-SHPP, lysing the cells, and then incubating them with 125 I-sulfo-SHPP. Exclusive labeling of either side of the plasma membrane was demonstrated by the labeling of some marker proteins with well-defined spacial orientations on erythroctyes. Transmembrane proteins such as the epidermal growth factor receptor on cultured cells could also be labeled differentially from either side of the plasma membrane

Fabrication mechanism of friction-induced selective etching on Si(100) surface.

Science.gov (United States)

Guo, Jian; Song, Chenfei; Li, Xiaoying; Yu, Bingjun; Dong, Hanshan; Qian, Linmao; Zhou, Zhongrong

2012-02-23

As a maskless nanofabrication technique, friction-induced selective etching can easily produce nanopatterns on a Si(100) surface. Experimental results indicated that the height of the nanopatterns increased with the KOH etching time, while their width increased with the scratching load. It has also found that a contact pressure of 6.3 GPa is enough to fabricate a mask layer on the Si(100) surface. To understand the mechanism involved, the cross-sectional microstructure of a scratched area was examined, and the mask ability of the tip-disturbed silicon layer was studied. Transmission electron microscope observation and scanning Auger nanoprobe analysis suggested that the scratched area was covered by a thin superficial oxidation layer followed by a thick distorted (amorphous and deformed) layer in the subsurface. After the surface oxidation layer was removed by HF etching, the residual amorphous and deformed silicon layer on the scratched area can still serve as an etching mask in KOH solution. The results may help to develop a low-destructive, low-cost, and flexible nanofabrication technique suitable for machining of micro-mold and prototype fabrication in micro-systems.

A size selective porous silicon grating-coupled Bloch surface and sub-surface wave biosensor.

Science.gov (United States)

Rodriguez, Gilberto A; Ryckman, Judson D; Jiao, Yang; Weiss, Sharon M

2014-03-15

A porous silicon (PSi) grating-coupled Bloch surface and sub-surface wave (BSW/BSSW) biosensor is demonstrated to size selectively detect the presence of both large and small molecules. The BSW is used to sense large immobilized analytes at the surface of the structure while the BSSW that is confined inside but near the top of the structure is used to sensitively detect small molecules. Functionality of the BSW and BSSW modes is theoretically described by dispersion relations, field confinements, and simulated refractive index shifts within the structure. The theoretical results are experimentally verified by detecting two different small chemical molecules and one large 40 base DNA oligonucleotide. The PSi-BSW/BSSW structure is benchmarked against current porous silicon technology and is shown to have a 6-fold higher sensitivity in detecting large molecules and a 33% improvement in detecting small molecules. This is the first report of a grating-coupled BSW biosensor and the first report of a BSSW propagating mode. © 2013 Published by Elsevier B.V.

40 CFR 761.306 - Sampling 1 meter square surfaces by random selection of halves.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Sampling 1 meter square surfaces by...(b)(3) § 761.306 Sampling 1 meter square surfaces by random selection of halves. (a) Divide each 1 meter square portion where it is necessary to collect a surface wipe test sample into two equal (or as...

Frequency selective surfaces based high performance microstrip antenna

CERN Document Server

Narayan, Shiv; Jha, Rakesh Mohan

2016-01-01

This book focuses on performance enhancement of printed antennas using frequency selective surfaces (FSS) technology. The growing demand of stealth technology in strategic areas requires high-performance low-RCS (radar cross section) antennas. Such requirements may be accomplished by incorporating FSS into the antenna structure either in its ground plane or as the superstrate, due to the filter characteristics of FSS structure. In view of this, a novel approach based on FSS technology is presented in this book to enhance the performance of printed antennas including out-of-band structural RCS reduction. In this endeavor, the EM design of microstrip patch antennas (MPA) loaded with FSS-based (i) high impedance surface (HIS) ground plane, and (ii) the superstrates are discussed in detail. The EM analysis of proposed FSS-based antenna structures have been carried out using transmission line analogy, in combination with the reciprocity theorem. Further, various types of novel FSS structures are considered in desi...

All-cellulose composites of regenerated cellulose fibres by surface selective dissolution

NARCIS (Netherlands)

Soykeabkaew, N.; Nishino, T.; Peijs, Ton

2009-01-01

All-cellulose composites of Lyocell and high modulus/strength cellulose fibres were successfully prepared using a surface selective dissolution method. The effect of immersion time of the fibres in the solvent during composite's preparation and the effect of the starting fibre's structure on their

Synthesis of water soluble glycine capped silver nanoparticles and their surface selective interaction

International Nuclear Information System (INIS)

Agasti, Nityananda; Singh, Vinay K.; Kaushik, N.K.

2015-01-01

Highlights: • Synthesis of water soluble silver nanoparticles at ambient reaction conditions. • Glycine as stabilizing agent for silver nanoparticles. • Surface selective interaction of glycine with silver nanoparticles. • Glycine concentration influences crystalinity and optical property of silver nanoparticles. - Abstract: Synthesis of biocompatible metal nanoparticles has been an area of significant interest because of their wide range of applications. In the present study, we have successfully synthesized water soluble silver nanoparticles assisted by small amino acid glycine. The method is primarily based on reduction of AgNO 3 with NaBH 4 in aqueous solution under atmospheric air in the presence of glycine. UV–vis spectroscopy, transmission electron microscopy (TEM), X–ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, thermogravimetry (TG) and differential thermal analysis (DTA) techniques used for characterization of resulting silver nanoparticles demonstrated that, glycine is an effective capping agent to stabilize silver nanoparticles. Surface selective interaction of glycine on (1 1 1) face of silver nanoparticles has been investigated. The optical property and crystalline behavior of silver nanoparticles were found to be sensitive to concentration of glycine. X–ray diffraction studies ascertained the phase specific interaction of glycine on silver nanoparticles. Silver nanoparticles synthesized were of diameter 60 nm. We thus demonstrated an efficient synthetic method for synthesis of water soluble silver nanoparticles capped by amino acid under mild reaction conditions with excellent reproducibility

Mining for diagnostic information in body surface potential maps: A comparison of feature selection techniques

Directory of Open Access Journals (Sweden)

McCullagh Paul J

2005-09-01

Full Text Available Abstract Background In body surface potential mapping, increased spatial sampling is used to allow more accurate detection of a cardiac abnormality. Although diagnostically superior to more conventional electrocardiographic techniques, the perceived complexity of the Body Surface Potential Map (BSPM acquisition process has prohibited its acceptance in clinical practice. For this reason there is an interest in striking a compromise between the minimum number of electrocardiographic recording sites required to sample the maximum electrocardiographic information. Methods In the current study, several techniques widely used in the domains of data mining and knowledge discovery have been employed to mine for diagnostic information in 192 lead BSPMs. In particular, the Single Variable Classifier (SVC based filter and Sequential Forward Selection (SFS based wrapper approaches to feature selection have been implemented and evaluated. Using a set of recordings from 116 subjects, the diagnostic ability of subsets of 3, 6, 9, 12, 24 and 32 electrocardiographic recording sites have been evaluated based on their ability to correctly asses the presence or absence of Myocardial Infarction (MI. Results It was observed that the wrapper approach, using sequential forward selection and a 5 nearest neighbour classifier, was capable of choosing a set of 24 recording sites that could correctly classify 82.8% of BSPMs. Although the filter method performed slightly less favourably, the performance was comparable with a classification accuracy of 79.3%. In addition, experiments were conducted to show how (a features chosen using the wrapper approach were specific to the classifier used in the selection model, and (b lead subsets chosen were not necessarily unique. Conclusion It was concluded that both the filter and wrapper approaches adopted were suitable for guiding the choice of recording sites useful for determining the presence of MI. It should be noted however

A kinetic analysis of manual wheelchair propulsion during start-up on select indoor and outdoor surfaces

NARCIS (Netherlands)

Koontz, AM; Cooper, RA; Boninger, ML; Yang, YS; Impink, BG; van der Woude, LHV

2005-01-01

The objective of this study was to conduct a kinetic analysis of manual wheelchair propulsion during start-LIP on select indoor and Outdoor surfaces. Eleven manual wheelchairs were fitted with a SMART(Wheel) and their users were asked to Push on a Course consisting of high- and low-pile carpet,

Selective appearance of several laser-induced periodic surface structure patterns on a metal surface using structural colors produced by femtosecond laser pulses

Energy Technology Data Exchange (ETDEWEB)

Yao Jianwu; Zhang Chengyun; Liu Haiying; Dai Qiaofeng; Wu Lijun [Laboratory of Photonic Information Technology, School of Information and Optoelectronic Science and Engineering, South China Normal University, Guangzhou 510006 (China); Lan, Sheng, E-mail: slan@scnu.edu.cn [Laboratory of Photonic Information Technology, School of Information and Optoelectronic Science and Engineering, South China Normal University, Guangzhou 510006 (China); Gopal, Achanta Venu [Department of Condensed Matter Physics and Material Science, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005 (India); Trofimov, Vyacheslav A.; Lysak, Tatiana M. [Department of Computational Mathematics and Cybernetics, M. V. Lomonosov Moscow State University, Moscow 119992 (Russian Federation)

2012-07-15

Ripples with a subwavelength period were induced on the surface of a stainless steel (301 L) foil by femtosecond laser pulses. By optimizing the irradiation fluence of the laser pulses and the scanning speed of the laser beam, ripples with large amplitude ({approx}150 nm) and uniform period could be obtained, rendering vivid structural colors when illuminating the surface with white light. It indicates that these ripples act as a surface grating that diffracts light efficiently. The strong dependence of the ripple orientation on the polarization of laser light offers us the opportunity of decorating different regions of the surface with different types of ripples. As a result, different patterns can be selectively displayed with structural color when white light is irradiated on the surface from different directions. More interestingly, we demonstrated the possibility of decorating the same region with two or more types of ripples with different orientations. In this way, different patterns with spatial overlapping can be selectively displayed with structural color. This technique may find applications in the fields of anti-counterfeiting, color display, decoration, encryption and optical data storage.

Rapid and selective removal of composite from tooth surfaces with a 9.3 µm CO2 laser using spectral feedback.

Science.gov (United States)

Chan, Kenneth H; Hirasuna, Krista; Fried, Daniel

2011-09-01

Dental composite restorative materials are color matched to the tooth and are difficult to remove by mechanical means without excessive removal or damage to peripheral enamel and dentin. Lasers are ideally suited for selective ablation to minimize healthy tissue loss when replacing existing restorations, sealants, or removing composite adhesives such as residual composite left after debonding orthodontic brackets. In this study, a carbon dioxide laser operating at 9.3-µm with a pulse duration of 10-20-microsecond and a pulse repetition rate of ∼200 Hz was integrated with a galvanometer based scanner and used to selectively remove composite from tooth surfaces. Spectra of the plume emission were acquired after each laser pulse and used to differentiate between the ablation of dental enamel or composite. Microthermocouples were used to monitor the temperature rise in the pulp chamber during composite removal. The composite was placed on tooth buccal and occlusal surfaces and the carbon dioxide laser beam was scanned across the surface to selectively remove the composite without excessive damage to the underlying sound enamel. The residual composite and the damage to the underlying enamel was evaluated using optical microscopy. The laser was able to rapidly remove composite from tooth buccal and occlusal surfaces with minimal damage to the underlying sound enamel and without excessive heat accumulation in the tooth. This study demonstrated that composite can be selectively removed from tooth surfaces at clinically relevant rates using a CO(2) laser operating at 9.3-µm with high pulse repetition rates with minimal heat deposition and damage to the underlying enamel. Copyright © 2011 Wiley-Liss, Inc.

The present and future on surface analysis for corrosion study

International Nuclear Information System (INIS)

Ohtsuka, Toshiaki

2015-01-01

Surface analysis for corrosion study was reviewed. For the study, the in-situ analysis was desired to describe the real feature. Light i.e., electromagnetic wave from gamma rays to infrared light has been used for the in-situ measurement of the corroded surface, although various ideas should be introduced for the study. For the application of the electromagnetic waves, a suitable window material and a suitable distance between the window and specimen surface depending on the properties of the wave must be selected. Electron spectroscopy including X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) is not applicable for the in-situ study and, however, it is very available for the corrosion study from the following points; elemental analysis, state analysis of the element, and microscopic analysis. In future, the tip enhance Raman scattering (TERS) for which the scanning probe microscopy (SPM) is combined with the surface enhanced Raman scattering (SERS) may be useful for the in-situ corrosion study. (author)

LASER INDUCED SELECTIVE ACTIVATION UTILIZING AUTO-CATALYTIC ELECTROLESS PLATING ON POLYMER SURFACE

DEFF Research Database (Denmark)

Zhang, Yang; Nielsen, Jakob Skov; Tang, Peter Torben

2009-01-01

. Characterization of the deposited copper layer was used to select and improve laser parameters. Several types of polymers with different melting points were used as substrate. Using the above mentioned laser treatment, standard grades of thermoplastic materials such as ABS, SAN, PE, PC and others have been......This paper presents a new method for selective micro metallization of polymers induced by laser. An Nd: YAG laser was employed to draw patterns on polymer surfaces using a special set-up. After subsequent activation and auto-catalytic electroless plating, copper only deposited on the laser tracks....... Induced by the laser, porous and rough structures are formed on the surface, which favours the palladium attachment during the activation step prior to the metallization. Laser focus detection, scanning electron microscopy (SEM) and other instruments were used to analyze the topography of the laser track...

Investigation of Selective Laser Melting Surface Alloyed Aluminium Metal Matrix Dispersive Reinforced Layers

Science.gov (United States)

Kamburov, V. V.; Dimitrova, R. B.; Kandeva, M. K.; Sofronov, Y. P.

2018-01-01

The aim of the paper is to investigate the improvement of mechanical properties and in particular wear resistance of laser surface alloyed dispersive reinforced thin layers produced by selective laser melting (SLM) technology. The wear resistance investigation of aluminium matrix composite layers in the conditions of dry friction surface with abrasive particles and nanoindentation tests were carried out. The process parameters (as scan speed) and their impact on the wear resistant layers have been evaluated. The alloyed layers containing metalized SiC particles were studied by Optical and Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray microanalysis (EDX). The obtained experimental results of the laser alloyed thin layers show significant development of their wear resistance and nanohardness due to the incorporated reinforced phase of electroless nickel coated SiC particles.

In Situ SIMS and IR Spectroscopy of Well-Defined Surfaces Prepared by Soft Landing of Mass-Selected Ions

Energy Technology Data Exchange (ETDEWEB)

Johnson, Grant E.; Gunaratne, Kalupathirannehelage Don D.; Laskin, Julia

2014-06-16

Soft landing of mass-selected ions onto surfaces is a powerful approach for the highly-controlled preparation of materials that are inaccessible using conventional synthesis techniques. Coupling soft landing with in situ characterization using secondary ion mass spectrometry (SIMS) and infrared reflection absorption spectroscopy (IRRAS) enables analysis of well-defined surfaces under clean vacuum conditions. The capabilities of three soft-landing instruments constructed in our laboratory are illustrated for the representative system of surface-bound organometallics prepared by soft landing of mass-selected ruthenium tris(bipyridine) dications, [Ru(bpy)3]2+, onto carboxylic acid terminated self-assembled monolayer surfaces on gold (COOH-SAMs). In situ time-of-flight (TOF)-SIMS provides insight into the reactivity of the soft-landed ions. In addition, the kinetics of charge reduction, neutralization and desorption occurring on the COOH-SAM both during and after ion soft landing are studied using in situ Fourier transform ion cyclotron resonance (FT-ICR)-SIMS measurements. In situ IRRAS experiments provide insight into how the structure of organic ligands surrounding metal centers is perturbed through immobilization of organometallic ions on COOH-SAM surfaces by soft landing. Collectively, the three instruments provide complementary information about the chemical composition, reactivity and structure of well-defined species supported on surfaces.

Investigation of selected surface integrity features of duplex stainless steel (DSS after turning

Directory of Open Access Journals (Sweden)

G. Krolczyk

2015-01-01

Full Text Available The article presents surface roughness profiles and Abbott - Firestone curves with vertical and amplitude parameters of surface roughness after turning by means of a coated sintered carbide wedge with a coating with ceramic intermediate layer. The investigation comprised the influence of cutting speed on the selected features of surface integrity in dry machining. The material under investigation was duplex stainless steel with two-phase ferritic-austenitic structure. The tests have been performed under production conditions during machining of parts for electric motors and deep-well pumps. The obtained results allow to draw conclusions about the characteristics of surface properties of the machined parts.

Surface modification of polycaprolactone scaffolds fabricated via selective laser sintering for cartilage tissue engineering

International Nuclear Information System (INIS)

Chen, Chih-Hao; Lee, Ming-Yih; Shyu, Victor Bong-Hang; Chen, Yi-Chieh; Chen, Chien-Tzung; Chen, Jyh-Ping

2014-01-01

Surface modified porous polycaprolactone scaffolds fabricated via rapid prototyping techniques were evaluated for cartilage tissue engineering purposes. Polycaprolactone scaffolds manufactured by selective laser sintering (SLS) were surface modified through immersion coating with either gelatin or collagen. Three groups of scaffolds were created and compared for both mechanical and biological properties. Surface modification with collagen or gelatin improved the hydrophilicity, water uptake and mechanical strength of the pristine scaffold. From microscopic observations and biochemical analysis, collagen-modified scaffold was the best for cartilage tissue engineering in terms of cell proliferation and extracellular matrix production. Chondrocytes/collagen-modified scaffold constructs were implanted subdermally in the dorsal spaces of female nude mice. Histological and immunohistochemical staining of the retrieved implants after 8 weeks revealed enhanced cartilage tissue formation. We conclude that collagen surface modification through immersion coating on SLS-manufactured scaffolds is a feasible scaffold for cartilage tissue engineering in craniofacial reconstruction. - Highlights: • Selective laser sintered polycaprolactone scaffolds are prepared. • Scaffolds are surface modified through immersion coating with gelatin or collagen. • Collagen-scaffold is the best for cartilage tissue engineering in vitro. • Chondrocytes/collagen-scaffold reveals enhanced cartilage tissue formation in vivo

Surface modification of polycaprolactone scaffolds fabricated via selective laser sintering for cartilage tissue engineering

Energy Technology Data Exchange (ETDEWEB)

Chen, Chih-Hao [Department of Chemical and Materials Engineering, Chang Gung University, Kweishan, Taoyuan 333, Taiwan, ROC (China); Department of Plastic and Reconstructive Surgery, Chang Gung Memorial Hospital, Craniofacial Research Center, Chang Gung University, Kweishann, Taoyuan 333, Taiwan, ROC (China); Lee, Ming-Yih [Graduate Institute of Medical Mechatronics, Chang Gung University, Kweishan, Taoyuan 333, Taiwan, ROC (China); Shyu, Victor Bong-Hang; Chen, Yi-Chieh; Chen, Chien-Tzung [Department of Plastic and Reconstructive Surgery, Chang Gung Memorial Hospital, Craniofacial Research Center, Chang Gung University, Kweishann, Taoyuan 333, Taiwan, ROC (China); Chen, Jyh-Ping, E-mail: jpchen@mail.cgu.edu.tw [Department of Chemical and Materials Engineering, Chang Gung University, Kweishan, Taoyuan 333, Taiwan, ROC (China); Research Center for Industry of Human Ecology, Chang Gung University of Science and Technology, Kweishan, Taoyuan 333, Taiwan, ROC (China)

2014-07-01

Surface modified porous polycaprolactone scaffolds fabricated via rapid prototyping techniques were evaluated for cartilage tissue engineering purposes. Polycaprolactone scaffolds manufactured by selective laser sintering (SLS) were surface modified through immersion coating with either gelatin or collagen. Three groups of scaffolds were created and compared for both mechanical and biological properties. Surface modification with collagen or gelatin improved the hydrophilicity, water uptake and mechanical strength of the pristine scaffold. From microscopic observations and biochemical analysis, collagen-modified scaffold was the best for cartilage tissue engineering in terms of cell proliferation and extracellular matrix production. Chondrocytes/collagen-modified scaffold constructs were implanted subdermally in the dorsal spaces of female nude mice. Histological and immunohistochemical staining of the retrieved implants after 8 weeks revealed enhanced cartilage tissue formation. We conclude that collagen surface modification through immersion coating on SLS-manufactured scaffolds is a feasible scaffold for cartilage tissue engineering in craniofacial reconstruction. - Highlights: • Selective laser sintered polycaprolactone scaffolds are prepared. • Scaffolds are surface modified through immersion coating with gelatin or collagen. • Collagen-scaffold is the best for cartilage tissue engineering in vitro. • Chondrocytes/collagen-scaffold reveals enhanced cartilage tissue formation in vivo.

Surface-Selective Preferential Production of Reactive Oxygen Species on Piezoelectric Ceramics for Bacterial Killing

OpenAIRE

Tan, Guoxin; Wang, Shuangying; Zhu, Ye; Zhou, Lei; Yu, Peng; Wang, Xiaolan; He, Tianrui; Chen, Junqi; Mao, Chuanbin; Ning, Chengyun

2016-01-01

Reactive oxygen species (ROS) can be used to kill bacterial cells, and thus the selective generation of ROS from material surfaces is an emerging direction in antibacterial material discovery. We found the polarization of piezoelectric ceramic causes the two sides of the disk to become positively and negatively charged, which translate into cathode and anode surfaces in an aqueous solution. Because of the microelectrolysis of water, ROS are preferentially formed on the cathode surface. Conseq...

Angular scanning and variable wavelength surface plasmon resonance allowing free sensor surface selection for optimum material- and bio-sensing

NARCIS (Netherlands)

Lakayan, Dina; Tuppurainen, Jussipekka; Albers, Martin; van Lint, Matthijs J.; van Iperen, Dick J.; Weda, Jelmer J.A.; Kuncova-Kallio, Johana; Somsen, Govert W.; Kool, Jeroen

2018-01-01

A variable-wavelength Kretschmann configuration surface plasmon resonance (SPR) apparatus with angle scanning is presented. The setup provides the possibility of selecting the optimum wavelength with respect to the properties of the metal layer of the sensorchip, sample matrix, and biomolecular

3D SEM for surface topography quantification – a case study on dental surfaces

International Nuclear Information System (INIS)

Glon, F; Flys, O; Lööf, P-J; Rosén, B-G

2014-01-01

3D analysis of surface topography is becoming a more used tool for industry and research. New ISO standards are being launched to assist in quantifying engineering surfaces. The traditional optical measuring instrumentation used for 3D surface characterization has been optical interferometers and confocal based instrumentation. However, the resolution here is limited in the lateral dimension to the wavelength of visible light to about 500 nm. The great advantage using the SEM for topography measurements is the high flexibility to zoom from low magnifications and locating interesting areas to high magnification of down to nanometer large surface features within seconds. This paper presents surface characterization of dental implant micro topography. 3D topography data was created from SEM images using commercial photogrammetric software. A coherence scanning interferometer was used for reference measurements to compare with the 3D SEM measurements on relocated areas. As a result of this study, measurements emphasizes that the correlation between the accepted CSI measurements and the new technology represented by photogrammetry based on SEM images for many areal characterization parameters are around or less than 20%. The importance of selecting sampling and parameter sensitivity to varying sampling is high-lighted. Future work includes a broader study of limitations of the photogrammetry technique on certified micro-geometries and more application surfaces at different scales

Mg-Fe-mixed oxides derived from layered double hydroxides: A study of the surface properties

Directory of Open Access Journals (Sweden)

Marinković-Nedučin Radmila P.

2011-01-01

Full Text Available The influence of surface properties on the selectivity of the synthesized catalysts was studied, considering that their selectivity towards particular hydrocarbons is crucial for their overall activity in the chosen Fischer- -Tropsch reaction. Magnesium- and iron-containing layered double hydroxides (LDH, with the general formula: [Mg1-xFex(OH2](CO3x/2?mH2O, x = = n(Fe/(n(Mg+n(Fe, synthesized with different Mg/Fe ratio and their thermally derived mixed oxides were investigated. Magnesium was chosen because of its basic properties, whereas iron was selected due to its well-known high Fischer-Tropsch activity, redox properties and the ability to form specific active sites in the layered LDH structure required for catalytic application. The thermally less stable multiphase system (synthesized outside the optimal single LDH phase range with additional Fe-phase, having a lower content of surface acid and base active sites, a lower surface area and smaller fraction of smaller mesopores, showed higher selectivity in the Fischer-Tropsch reaction. The results of this study imply that the metastability of derived multiphase oxides structure has a greater influence on the formation of specific catalyst surface sites than other investigated surface properties.

Effect of the selective adsorption on the reactive scattering process of molecular beams from stepped surfaces

International Nuclear Information System (INIS)

Garcia, N.

1977-01-01

An indicative proposal which may explain the diffusion of incident atomic beams scattered by a crystal surface is made in terms of the selective adsorption mechanism. In this sense, the stepped metallic surfaces present characteristics which enhance the displacements and the lifetimes of the beams on the surface. This may be important for increasing the exchange reactive scattering of molecules from crystal surfaces

Cobalt oxide films for solar selective surfaces, obtained by spray pyrolisis

Energy Technology Data Exchange (ETDEWEB)

Avila G, A. [Departmento de Ingenieria Electrica, Seccion de Electronica del Estado Solido, CINVESTAV del I.P.N., Av. I.P.N. no. 2508, Ap. Postal 14-740, Mexico D. F., 07360 (Mexico); Barrera C, E. [Departamento de IPH, Area de Ingenieria en Recursos Energeticos, Universidad Autonoma Metropolitana-Iztapalapa, Ap. Postal 55-5340, Mexico, D. F. (Mexico); Huerta A, L.; Muhl, S. [Instituto de Investigaciones en Materiales, UNAM, Mexico, D.F. 04510 (Mexico)

2004-05-01

Cobalt oxide films upon stainless steel substrates were deposited by using the pneumatic spray pyrolisis technique, starting from an inorganic salt (CoNO{sub 3}{center_dot}3H{sub 2}O) dissolved in a water-alcohol mixture. Stainless steel and nickeled stainless steel substrates were used. Absorptance and emittance, for selective surface applications, were evaluated from reflectance measurements in the UV-Vis and infrared ranges. X-ray diffraction, XPS and AFM measurements were done. The predominant cobalt phase is Co{sub 3}O{sub 4}, but also CoO and Co{sub 2}O{sub 3} phases, besides metallic cobalt, were detected. Films upon nickeled steel substrates at 400C exhibit high absorptances (0.86), but also the emittance is high (0.43), yielding a selectivity of 2.0. A similar film on steel substrate reaches only a figure of 0.77 absorptance, but the thermal emittance remains low (0.20), giving a selectivity of 3.85. These films are good prospects for selective solar absorption coatings.

Surface chemistry of Ti6Al4V components fabricated using selective laser melting for biomedical applications.

Science.gov (United States)

Vaithilingam, Jayasheelan; Prina, Elisabetta; Goodridge, Ruth D; Hague, Richard J M; Edmondson, Steve; Rose, Felicity R A J; Christie, Steven D R

2016-10-01

Selective laser melting (SLM) has previously been shown to be a viable method for fabricating biomedical implants; however, the surface chemistry of SLM fabricated parts is poorly understood. In this study, X-ray photoelectron spectroscopy (XPS) was used to determine the surface chemistries of (a) SLM as-fabricated (SLM-AF) Ti6Al4V and (b) SLM fabricated and mechanically polished (SLM-MP) Ti6Al4V samples and compared with (c) traditionally manufactured (forged) and mechanically polished Ti6Al4V samples. The SLM-AF surface was observed to be porous with an average surface roughness (Ra) of 17.6±3.7μm. The surface chemistry of the SLM-AF was significantly different to the FGD-MP surface with respect to elemental distribution and their existence on the outermost surface. Sintered particles on the SLM-AF surface were observed to affect depth profiling of the sample due to a shadowing effect during argon ion sputtering. Surface heterogeneity was observed for all three surfaces; however, vanadium was witnessed only on the mechanically polished (SLM-MP and FGD-MP) surfaces. The direct and indirect 3T3 cell cytotoxicity studies revealed that the cells were viable on the SLM fabricated Ti6Al4V parts. The varied surface chemistry of the SLM-AF and SLM-MP did not influence the cell behaviour. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

A new experimental setup for high-pressure catalytic activity measurements on surface deposited mass-selected Pt clusters

International Nuclear Information System (INIS)

Watanabe, Yoshihide; Isomura, Noritake

2009-01-01

A new experimental setup to study catalytic and electronic properties of size-selected clusters on metal oxide substrates from the viewpoint of cluster-support interaction and to formulate a method for the development of heterogeneous catalysts such as automotive exhaust catalysts has been developed. The apparatus consists of a size-selected cluster source, a photoemission spectrometer, a scanning tunneling microscope (STM), and a high-pressure reaction cell. The high-pressure reaction cell measurements provided information on catalytic properties in conditions close to practical use. The authors investigated size-selected platinum clusters deposited on a TiO 2 (110) surface using a reaction cell and STM. Catalytic activity measurements showed that the catalytic activities have a cluster-size dependency.

In vitro cell-biological performance and structural characterization of selective laser sintered and plasma surface functionalized polycaprolactone scaffolds for bone regeneration

Energy Technology Data Exchange (ETDEWEB)

Van Bael, Simon, E-mail: simon.vanbael@mech.kuleuven.be [Department of Mechanical Engineering, Division of Production Engineering, Machine Design and Automation, Katholieke Universiteit Leuven, Celestijnenlaan 300b, 3001 Leuven (Belgium); Department of Mechanical Engineering, Division of Biomechanics and Engineering Design, Katholieke Universiteit Leuven, Celestijnenlaan 300c, bus 2419, 3001 Heverlee (Belgium); Prometheus, Division of Skeletal Tissue Engineering, Katholieke Universiteit Leuven, O and N 1, Herestraat 49, bus 813, 3000 Leuven (Belgium); Desmet, Tim [Polymer Chemistry and Biomaterials Research Group, Ghent University, Krijgslaan 281 S4 Bis, Ghent, 9000 (Belgium); Research Unit Plasma Technology (RUPT), Department of Applied Physics, Faculty of Engineering, Ghent University, Jozef Plateaustraat 22, 9000 Ghent (Belgium); Chai, Yoke Chin [Prometheus, Division of Skeletal Tissue Engineering, Katholieke Universiteit Leuven, O and N 1, Herestraat 49, bus 813, 3000 Leuven (Belgium); Pyka, Gregory [Prometheus, Division of Skeletal Tissue Engineering, Katholieke Universiteit Leuven, O and N 1, Herestraat 49, bus 813, 3000 Leuven (Belgium); Department of Metallurgy and Materials Engineering, Katholieke Universiteit Leuven, Kasteelpark Arenberg 44, bus 2450, 3001 Leuven (Belgium); Dubruel, Peter [Polymer Chemistry and Biomaterials Research Group, Ghent University, Krijgslaan 281 S4 Bis, Ghent, 9000 (Belgium); Research Unit Plasma Technology (RUPT), Department of Applied Physics, Faculty of Engineering, Ghent University, Jozef Plateaustraat 22, 9000 Ghent (Belgium); Kruth, Jean-Pierre [Department of Mechanical Engineering, Division of Production Engineering, Machine Design and Automation, Katholieke Universiteit Leuven, Celestijnenlaan 300b, 3001 Leuven (Belgium); Schrooten, Jan [Prometheus, Division of Skeletal Tissue Engineering, Katholieke Universiteit Leuven, O and N 1, Herestraat 49, bus 813, 3000 Leuven (Belgium)

2013-08-01

In the present study a structural characterization and in vitro cell-biological evaluation was performed on polycaprolactone (PCL) scaffolds that were produced by the additive manufacturing technique selective laser sintering (SLS), followed by a plasma-based surface modification technique, either non-thermal oxygen plasma or double protein coating, to functionalize the PCL scaffold surfaces. In the first part of this study pore morphology by means of 2D optical microscopy, surface chemistry by means of hydrophilicity measurement and X-ray photoelectron spectroscopy, strut surface roughness by means of 3D micro-computed tomography (CT) imaging and scaffold mechanical properties by means of compression testing were evaluated before and after the surface modifications. The results showed that both surface modifications increased the PCL scaffold hydrophilicity without altering the morphological and mechanical properties. In the second part of this study the in vitro cell proliferation and differentiation of human osteoprogenitor cells, over 14 days of culture in osteogenic and growth medium were investigated. The O{sub 2} plasma modification gave rise to a significant lower in vitro cell proliferation compared to the untreated and double protein coated scaffolds. Furthermore the double protein coating increased in vitro cell metabolic activity and cell differentiation compared to the untreated and O{sub 2} plasma PCL scaffolds when OM was used. - Highlights: • Polycaprolactone scaffolds are produced with selective laser sintering. • 2 types of plasma based surface functionalization were applied. • Plasma had no significant effect on strut roughness and pore morphology. • Plasma improved surface hydrophilicity. • In vitro cell differentiation increased with plasma protein coated functionalization.

In vitro cell-biological performance and structural characterization of selective laser sintered and plasma surface functionalized polycaprolactone scaffolds for bone regeneration

International Nuclear Information System (INIS)

Van Bael, Simon; Desmet, Tim; Chai, Yoke Chin; Pyka, Gregory; Dubruel, Peter; Kruth, Jean-Pierre; Schrooten, Jan

2013-01-01

In the present study a structural characterization and in vitro cell-biological evaluation was performed on polycaprolactone (PCL) scaffolds that were produced by the additive manufacturing technique selective laser sintering (SLS), followed by a plasma-based surface modification technique, either non-thermal oxygen plasma or double protein coating, to functionalize the PCL scaffold surfaces. In the first part of this study pore morphology by means of 2D optical microscopy, surface chemistry by means of hydrophilicity measurement and X-ray photoelectron spectroscopy, strut surface roughness by means of 3D micro-computed tomography (CT) imaging and scaffold mechanical properties by means of compression testing were evaluated before and after the surface modifications. The results showed that both surface modifications increased the PCL scaffold hydrophilicity without altering the morphological and mechanical properties. In the second part of this study the in vitro cell proliferation and differentiation of human osteoprogenitor cells, over 14 days of culture in osteogenic and growth medium were investigated. The O 2 plasma modification gave rise to a significant lower in vitro cell proliferation compared to the untreated and double protein coated scaffolds. Furthermore the double protein coating increased in vitro cell metabolic activity and cell differentiation compared to the untreated and O 2 plasma PCL scaffolds when OM was used. - Highlights: • Polycaprolactone scaffolds are produced with selective laser sintering. • 2 types of plasma based surface functionalization were applied. • Plasma had no significant effect on strut roughness and pore morphology. • Plasma improved surface hydrophilicity. • In vitro cell differentiation increased with plasma protein coated functionalization

Selection Criteria and Methods for Testing Different Surface Materials for Contact Frying Processes

DEFF Research Database (Denmark)

Ashokkumar, Saranya

Inner surfaces of industrial process equipment for food are often coated to give the surfaces particular properties with respect to adhesion and cleanability. Existing coating materials (PTFE (Teflon®) or silicone based polymers) suffer from drawbacks when used in contact frying, because these co...... surface materials for contact frying processes. The surfaces selected for this purpose cover a wide spectrum of materials that range from hydrophobic to hydrophilic materials. The different surface materials investigated include stainless steel (reference), aluminium (Al Mg 5754), PTFE......, an experimental rig has been constructed which enabled a controlled fouling of different coatings on steel and aluminium substrates under realistic frying conditions. A subjective rating procedure was employed for screening different surfaces according to their non-stick properties when used for frying of a model...... defects and surface roughness play a significant role. The wear resistance of the coatings was tested by performing abrasive wear experiments. The ceramic coatings: TiAlN and ZrN were found to show the best wear resistance properties. The experiments also revealed the poor wear resistance of stainless...

Surfaces of Building Practice

OpenAIRE

Surynková, Petra

2009-01-01

My diploma thesis Surfaces of Building Practice deals with the basic properties of surfaces, their mathematical description, categorization, and application in technical practice. Each studied surface is defined and its process of construction and parametrical description is listed. The thesis studies selected types of surfaces in details - these surfaces include surfaces of revolution, ruled surfaces, screw surfaces, and translational surfaces. An application of each studied surfaces is show...

Generation of Cu–In alloy surfaces from CuInO2 as selective catalytic sites for CO2 electroreduction

KAUST Repository

Jedidi, Abdesslem

2015-08-11

The lack of availability of efficient, selective and stable electrocatalysts is a major hindrance for scalable CO2 reduction processes. Herein, we report the generation of Cu–In alloy surfaces for electrochemical reduction of CO2 from mixed metal oxides of CuInO2 as the starting material. The material successfully generates selective active sites to form CO from CO2 electroreduction at mild overpotentials. Density functional theory (DFT) indicates that the site occupation of the inert In occurs more on the specific sites of Cu. In addition, while In atoms do not preferentially adsorb H or CO, Cu atoms, which neighbor the In atoms, alters the preference of their adsorption. This preference for site occupation and altered adsorption may account for the improved selectivity over that observed for Cu metal. This study demonstrates an example of a scalable synthesis method of bimetallic surfaces utilized with the mixed oxide precursor having the diversity of metal choice, which may drastically alter the electrocatalytic performance, as presented herein.

Generation of Cu–In alloy surfaces from CuInO2 as selective catalytic sites for CO2 electroreduction

KAUST Repository

Jedidi, Abdesslem; Rasul, Shahid; Masih, Dilshad; Cavallo, Luigi; Takanabe, Kazuhiro

2015-01-01

The lack of availability of efficient, selective and stable electrocatalysts is a major hindrance for scalable CO2 reduction processes. Herein, we report the generation of Cu–In alloy surfaces for electrochemical reduction of CO2 from mixed metal oxides of CuInO2 as the starting material. The material successfully generates selective active sites to form CO from CO2 electroreduction at mild overpotentials. Density functional theory (DFT) indicates that the site occupation of the inert In occurs more on the specific sites of Cu. In addition, while In atoms do not preferentially adsorb H or CO, Cu atoms, which neighbor the In atoms, alters the preference of their adsorption. This preference for site occupation and altered adsorption may account for the improved selectivity over that observed for Cu metal. This study demonstrates an example of a scalable synthesis method of bimetallic surfaces utilized with the mixed oxide precursor having the diversity of metal choice, which may drastically alter the electrocatalytic performance, as presented herein.

Selective hydrodechlorination of 1,2-dichloroethane to ethylene over Pd-Ag/Al_2O_3 catalysts prepared by surface reduction

International Nuclear Information System (INIS)

Han, Yuxiang; Gu, Guangfeng; Sun, Jingya; Wang, Wenjuan; Wan, Haiqin; Xu, Zhaoyi; Zheng, Shourong

2015-01-01

Graphical abstract: - Highlights: • Surface reduction method was used for preparation of Pd-Ag(Cu) bimetallic catalysts. • Hydrodechlorination of 1,2-dichloroethane was investigated for production of ethylene. • Ag(Cu) selectively deposited on Pd surface during surface reduction process. • Ethylene selectivity was enhanced over Pd-Ag(Cu)/Al_2O_3 catalyst prepared by surface reduction. • Isolated Pd site is the key species for ethylene selectivity. - Abstract: Alumina supported Pd-Ag and (Cu) bimetallic catalysts (denoted as sr-Pd-Ag/Al_2O_3 or sr-Pd-Cu/Al_2O_3) with varied Pd/Ag (or Cu) ratios were prepared using the surface reduction method, and the gas-phase catalytic hydrodechlorination of 1,2-dichloroethane over the catalysts were investigated. For comparison, Pd-Ag bimetallic catalysts were prepared by the conventional co-impregnation method (denoted as im-Pd-Ag/Al_2O_3). The catalysts were characterized by N_2 adsorption, X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and CO chemisorption. Characterization results indicated that surface reduction led to selective deposition of metallic Ag on the surface of Pd particles, while Pd and Ag just disorderly mixed in the catalyst prepared by impregnation method. Therefore, sr-Pd-Ag/Al_2O_3 exhibited a higher ethylene selectivity than im-Pd-Ag/Al_2O_3 for hydrodechlorination of 1,2-dichloroethane at a similar Ag loading amount. Moreover, among sr-Pd-Ag/Al_2O_3, sr-Pd-Cu/Al_2O_3 and im-Pd-Ag/Al_2O_3 catalysts, the ethylene selectivity decreased over these catalysts following the order: sr-Pd-Ag/Al_2O_3 > sr-Pd-Cu/Al_2O_3 > im-Pd-Ag/Al_2O_3. The present results indicate that surface reduction can be used as a potential method to synthesize catalyst with enhanced ethylene selectivity in hydrodechlorination of 1,2-dichloroethane.

Surface decontamination studies using polyvinyl acetate based strippable polymer

International Nuclear Information System (INIS)

Rao, S.V.S.; Lal, K.B.

2004-01-01

Polyvinyl acetate based strippable polymer has been developed for surface decontamination. Stainless steel, mild steel, polyvinyl chloride and rubber have been selected as candidate materials for the radioactive decontamination studies. The ease of strippability and homogeneity of the polymer coating has been studied using infrared spectrophotometer. Decontamination of used radioactive respirator has been carried out and the peels obtained have been subjected to leaching and incineration studies. The infrared spectrophotometric studies also have been conducted to study the interaction between polyvinyl acetate and ions, like cesium, strontium and cobalt. (author)

Road surface erosion on the Jackson Demonstration State Forest: results of a pilot study

Science.gov (United States)

Brian Barrett; Rosemary Kosaka; David. Tomberlin

2012-01-01

This paper presents results of a 3 year pilot study of surface erosion on forest roads in the Jackson Demonstration State Forest in California’s coastal redwood region. Ten road segments representing a range of surface, grade, and ditch conditions were selected for the study. At each segment, settling basins with tipping buckets were installed to measure...

Thiol-ene thermosets exploiting surface reactivity for layer-by-layer structures and control of penetration depth for selective surface reactivity

DEFF Research Database (Denmark)

Daugaard, Anders Egede; Westh, Andreas; Pereira Rosinha Grundtvig, Ines

Thiol-ene thermosets have been shown to be an efficient platform for preparation of functional polymer surfaces. Especially the effectiveness and versatility of the system has enabled a large variety of network properties to be obtained in a simple and straight-forward way. Due to its selectivity......, various thiols and allyl or other vinyl reactants can be used to obtain either soft and flexible1 or more rigid functional thermosets 2. The methodology permits use of etiher thermal or photochemical conditions both for matrix preparation as well as for surface functionalization. Due to excess reactive...... groups in thµe surface of thiol-ene thermosets, it is possible to prepare surface functional thermosets or to exploit the reactive groups for modular construction and subsequent chemical bonding. Here a different approach preparing monolithic layer-by-layer structures with controlled mechanical...

How to Select the most Relevant Roughness Parameters of a Surface: Methodology Research Strategy

Science.gov (United States)

Bobrovskij, I. N.

2018-01-01

In this paper, the foundations for new methodology creation which provides solving problem of surfaces structure new standards parameters huge amount conflicted with necessary actual floors quantity of surfaces structure parameters which is related to measurement complexity decreasing are considered. At the moment, there is no single assessment of the importance of a parameters. The approval of presented methodology for aerospace cluster components surfaces allows to create necessary foundation, to develop scientific estimation of surfaces texture parameters, to obtain material for investigators of chosen technological procedure. The methods necessary for further work, the creation of a fundamental reserve and development as a scientific direction for assessing the significance of microgeometry parameters are selected.

Use of surface electromyography in phonation studies: an integrative review

Science.gov (United States)

Balata, Patricia Maria Mendes; Silva, Hilton Justino da; Moraes, Kyvia Juliana Rocha de; Pernambuco, Leandro de Araújo; Moraes, Sílvia Regina Arruda de

2013-01-01

Summary Introduction: Surface electromyography has been used to assess the extrinsic laryngeal muscles during chewing and swallowing, but there have been few studies assessing these muscles during phonation. Objective: To investigate the current state of knowledge regarding the use of surface electromyography for evaluation of the electrical activity of the extrinsic muscles of the larynx during phonation by means of an integrative review. Method: We searched for articles and other papers in the PubMed, Medline/Bireme, and Scielo databases that were published between 1980 and 2012, by using the following descriptors: surface electromyography and voice, surface electromyography and phonation, and surface electromyography and dysphonia. The articles were selectedon the basis ofinclusion and exclusion criteria. Data Synthesis: This was carried out with a cross critical matrix. We selected 27 papers,i.e., 24 articles and 3 theses. The studies differed methodologically with regards to sample size and investigation techniques, making it difficult to compare them, but showed differences in electrical activity between the studied groups (dysphonicsubjects, non-dysphonicsubjects, singers, and others). Conclusion: Electromyography has clinical applicability when technical precautions with respect to application and analysis are obeyed. However, it is necessary to adopt a universal system of assessment tasks and related measurement techniques to allow comparisons between studies. PMID:25992030

Use of surface electromyography in phonation studies: an integrative review

Directory of Open Access Journals (Sweden)

Balata, Patricia Maria Mendes

2014-01-01

Full Text Available Introduction: Surface electromyography has been used to assess the extrinsic laryngeal muscles during chewing and swallowing, but there have been few studies assessing these muscles during phonation. Objective: To investigate the current state of knowledge regarding the use of surface electromyography for evaluation of the electrical activity of the extrinsic muscles of the larynx during phonation by means of an integrative review. Method: We searched for articles and other papers in the PubMed, Medline/Bireme, and Scielo databases that were published between 1980 and 2012, by using the following descriptors: surface electromyography and voice, surface electromyography and phonation, and surface electromyography and dysphonia. The articles were selectedon the basis ofinclusion and exclusion criteria. Data Synthesis: This was carried out with a cross critical matrix. We selected 27 papers,i.e., 24 articles and 3 theses. The studies differed methodologically with regards to sample size and investigation techniques, making it difficult to compare them, but showed differences in electrical activity between the studied groups (dysphonicsubjects, non-dysphonicsubjects, singers, and others. Conclusion: Electromyography has clinical applicability when technical precautions with respect to application and analysis are obeyed. However, it is necessary to adopt a universal system of assessment tasks and related measurement techniques to allow comparisons between studies.

Yeast surface display platform for rapid discovery of conformationally selective nanobodies

DEFF Research Database (Denmark)

McMahon, Conor; Baier, Alexander S.; Pascolutti, Roberta

2018-01-01

this problem, we report a fully in vitro platform for nanobody discovery based on yeast surface display. We provide a blueprint for identifying nanobodies, demonstrate the utility of the library by crystallizing a nanobody with its antigen, and most importantly, we utilize the platform to discover...... conformationally selective nanobodies to two distinct human GPCRs. To facilitate broad deployment of this platform, the library and associated protocols are freely available for nonprofit research....

A short-term study of the state of surface water acidification at Semenyih dam

International Nuclear Information System (INIS)

Kantasamy, Nesamalar; Sumari, S.M.; Salam, S.M.; Riniswani Aziz

2007-01-01

A short-term study was done to analyze the state of acidification of surface water at Semenyih Dam. This study is part of a continuous monitoring programme for Malaysia as a participatory country of EANET (Acid Monitoring Network in East Asia). Surface water samples were taken at selected points of the dam from February to December 2005. Temperature, electrical conductivity, pH, alkalinity, acid neutralizing capacity (ANC) as well as concentration of specific ionic species were measured, determined and analysed in this study. Present available sort-term study data indicates Semenyih Dam surface water is currently not undergoing acidification. (author)

Active sites in the alkylation of toluene with methanol : a study by selective acid-base poisoning

NARCIS (Netherlands)

Borgna, A.; Sepulveda, J.; Magni, S.I.; Apesteguia, C.R.

2004-01-01

Selective acid–base poisoning of the alkylation of toluene with methanol was studied over alkali and alkaline-earth exchanged Y zeolites. Surface acid–base properties of the samples were determined by infrared spectroscopy using carbon dioxide and pyridine as probe molecules. Selective poisoning

How does the surface treatment change the cytocompatibility of implants made by selective laser melting?

Science.gov (United States)

Matouskova, Lucie; Ackermann, Michal; Horakova, Jana; Capek, Lukas; Henys, Petr; Safka, Jiri

2018-04-01

The study investigates the potential for producing medical components via Selective Laser Melting technology (SLM). The material tested consisted of the biocompatible titanium alloy Ti6Al4V. The research involved the testing of laboratory specimens produced using SLM technology both in vitro and for surface roughness. The aim of the research was to clarify whether SLM technology affects the cytocompatibility of implants and, thus, whether SLM implants provide suitable candidates for medical use following zero or minimum post-fabrication treatment. Areas covered: The specimens were tested with an osteoblast cell line and, subsequently, two post-treatment processes were compared: non-treated (as-fabricated) and glass-blasted. Interactions with MG-63 cells were evaluated by means of metabolic MTT assay and microscope techniques (scanning electron microscopy, fluorescence microscopy). Surface roughness was observed on both the non-treated and glass-blasted SLM specimens. Expert Commentary: The research concluded that the glass-blasting of SLM Ti6Al4V significantly reduces surface roughness. The arithmetic mean roughness Ra was calculated at 3.4 µm for the glass-blasted and 13.3 µm for the non-treated surfaces. However, the results of in vitro testing revealed that the non-treated surface was better suited to cell growth.

Fabrication of friction-reducing texture surface by selective laser melting of ink-printed (SLM-IP) copper (Cu) nanoparticles(NPs)

Science.gov (United States)

Wang, Xinjian; Liu, Junyan; Wang, Yang; Fu, Yanan

2017-02-01

This paper reports a process of selective laser melting of ink-printed (SLM-IP) copper (Cu) nanoparticles(NPs) for the fabrication of full dense Cu friction-reducing texture on the metallic surface in ambient condition. This technique synthesizes pure Cu by chemical reduction route using an organic solvent during laser melting in the atmosphere environment, and provides a flexible additive manufacture approach to form complex friction-reduction texture on the metallic surface. Microtextures of ring and disc arrays have been fabricated on the stainless steel surface by SLM-IP Cu NPs. The friction coefficient has been measured under the lubricating condition of the oil. Disc texture surface (DTS) has a relatively low friction coefficient compared with ring texture surface (RTS), Cu film surface (Cu-FS) and the untreated substrate. The study suggests a further research on SLM-IP approach for complex microstructure or texture manufacturing, possibly realizing its advantage of flexibility.

The Problem of Multiple Criteria Selection of the Surface Mining Haul Trucks

Science.gov (United States)

Bodziony, Przemysław; Kasztelewicz, Zbigniew; Sawicki, Piotr

2016-06-01

Vehicle transport is a dominant type of technological processes in rock mines, and its profit ability is strictly dependent on overall cost of its exploitation, especially on diesel oil consumption. Thus, a rational design of transportation system based on haul trucks should result from thorough analysis of technical and economic issues, including both cost of purchase and its further exploitation, having a crucial impact on the cost of minerals extraction. Moreover, off-highway trucks should be selected with respect to all specific exploitation conditions and even the user's preferences and experience. In this paper a development of universal family of evaluation criteria as well as application of evaluation method for haul truck selection process for a specific exploitation conditions in surface mining have been carried out. The methodology presented in the paper is based on the principles of multiple criteria decision aiding (MCDA) using one of the ranking method, i.e. ELECTRE III. The applied methodology has been allowed for ranking of alternative solution (variants), on the considered set of haul trucks. The result of the research is a universal methodology, and it consequently may be applied in other surface mines with similar exploitation parametres.

Frequency Selective Surface for Structural Health Monitoring

Science.gov (United States)

Norlyana Azemi, Saidatul; Mustaffa, Farzana Hazira Wan; Faizal Jamlos, Mohd; Abdullah Al-Hadi, Azremi; Soh, Ping Jack

2018-03-01

Structural health monitoring (SHM) technologies have attained attention to monitor civil structures. SHM sensor systems have been used in various civil structures such as bridges, buildings, tunnels and so on. However the previous sensor for SHM is wired and encounter with problem to cover large areas. Therefore, wireless sensor was introduced for SHM to reduce network connecting problem. Wireless sensors for Structural Health monitoring are new technology and have many advantages to overcome the drawback of conventional and wired sensor. This project proposed passive wireless SHM sensor using frequency selective surface (FSS) as an alternative to conventional sensors. The electromagnetic wave characteristic of FSS will change by geometrical changes of FSS due to mechanical strain or structural failure. The changes feature is used as a sensing function without any connecting wires. Two type of design which are circular ring and square loop along with the transmission and reflection characteristics of SHM using FSS were discussed in this project. A simulation process has shown that incident angle characteristics can be use as a data for SHM application.

Inversion of membrane surface charge by trivalent cations probed with a cation-selective channel.

Science.gov (United States)

Gurnev, Philip A; Bezrukov, Sergey M

2012-11-13

We demonstrate that the cation-selective channel formed by gramicidin A can be used as a reliable sensor for studying the multivalent ion accumulation at the surfaces of charged lipid membranes and the "charge inversion" phenomenon. In asymmetrically charged membranes with the individual leaflets formed from pure negative and positive lipids bathed by 0.1 M CsCl solutions the channel exhibits current rectification, which is comparable to that of a typical n/p semiconductor diode. We show that even at these highly asymmetrical conditions the channel conductance can be satisfactorily described by the electrodiffusion equation in the constant field approximation but, due to predictable limitations, only when the applied voltages do not exceed 50 mV. Analysis of the changes in the voltage-dependent channel conductance upon addition of trivalent cations allows us to gauge their interactions with the membrane surface. The inversion of the sign of the effective surface charge takes place at the concentrations, which correlate with the cation size. Specifically, these concentrations are close to 0.05 mM for lanthanum, 0.25 mM for hexaamminecobalt, and 4 mM for spermidine.

Pt Single Atoms Embedded in the Surface of Ni Nanocrystals as Highly Active Catalysts for Selective Hydrogenation of Nitro Compounds.

Science.gov (United States)

Peng, Yuhan; Geng, Zhigang; Zhao, Songtao; Wang, Liangbing; Li, Hongliang; Wang, Xu; Zheng, Xusheng; Zhu, Junfa; Li, Zhenyu; Si, Rui; Zeng, Jie

2018-06-13

Single-atom catalysts exhibit high selectivity in hydrogenation due to their isolated active sites, which ensure uniform adsorption configurations of substrate molecules. Compared with the achievement in catalytic selectivity, there is still a long way to go in exploiting the catalytic activity of single-atom catalysts. Herein, we developed highly active and selective catalysts in selective hydrogenation by embedding Pt single atoms in the surface of Ni nanocrystals (denoted as Pt 1 /Ni nanocrystals). During the hydrogenation of 3-nitrostyrene, the TOF numbers based on surface Pt atoms of Pt 1 /Ni nanocrystals reached ∼1800 h -1 under 3 atm of H 2 at 40 °C, much higher than that of Pt single atoms supported on active carbon, TiO 2 , SiO 2 , and ZSM-5. Mechanistic studies reveal that the remarkable activity of Pt 1 /Ni nanocrystals derived from sufficient hydrogen supply because of spontaneous dissociation of H 2 on both Pt and Ni atoms as well as facile diffusion of H atoms on Pt 1 /Ni nanocrystals. Moreover, the ensemble composed of the Pt single atom and nearby Ni atoms in Pt 1 /Ni nanocrystals leads to the adsorption configuration of 3-nitrostyrene favorable for the activation of nitro groups, accounting for the high selectivity for 3-vinylaniline.

Effects of annealing temperatures on the morphological, mechanical, surface chemical bonding, and solar selectivity properties of sputtered TiAlSiN thin films

International Nuclear Information System (INIS)

Rahman, M. Mahbubur; Jiang, Zhong-Tao; Zhou, Zhi-feng; Xie, Zonghan; Yin, Chun Yang; Kabir, Humayun; Haque, Md. Mahbubul; Amri, Amun; Mondinos, Nicholas; Altarawneh, Mohammednoor

2016-01-01

Quaternary sputtered TiAlSiN coatings were investigated for their high temperature structural stability, surface morphology, mechanical behaviors, surface chemical bonding states, solar absorptance and thermal emittance for possible solar selective surface applications. The TiAlSiN films were synthesized, via unbalanced magnetron sputtered technology, on AISI M2 steel substrate and annealed at 500 °C - 800 °C temperature range. SEM micrographs show nanocomposite-like structure with amorphous grain boundaries. Nanoindentation analyses indicate a decrease of hardness, plastic deformation and constant yield strength for the coatings. XPS analysis show mixed Ti, Al and Si nitride and oxide as main coating components but at 800 °C the top layer of the coatings is clearly composed of only Ti and Al oxides. Synchrotron radiation XRD (SR-XRD) results indicate various Ti, Al and Si nitride and oxide phases, for the above annealing temperature range with a phase change occurring with the Fe component of the substrate. UV–Vis spectroscopy, FTIR spectroscopy studies determined a high solar selectivity, s of 24.6 for the sample annealed at 600 °C. Overall results show good structural and morphological stability of these coatings at temperatures up to 800 °C with a very good solar selectivity for real world applications. - Highlights: • TiAlSiN sputtered coatings were characterized for solar selective applications. • In situ synchrotron radiation XRD were studies show the occurrence of multiple stable phases. • A high selectivity of 24.63 has been achieved for the coatings annealed at 700 °C. • Existence of XRD phases were also confirmed by XPS measurements. • At high temperature annealing the mechanical properties of films were governed by the utmost surfaces of the films.

Trends in the Hydrodeoxygenation Activity and Selectivity of Transition Metal Surfaces

DEFF Research Database (Denmark)

Lausche, Adam C.; Falsig, Hanne; Jensen, Anker Degn

2014-01-01

This paper reports the use of a combination of density functional theory and microkinetic modelling to establish trends in the hydrodeoxygenation rates and selectivites of transition metal surfaces. Biomass and biomass-derived chemicals often contain large fractions of oxygenates. Removal...... of the oxygen through hydrotreating represents one strategy for producing commodity chemicals from these renewable materials. Using the model developed in this paper, we predict ethylene glycol hydrodeoxygenation selectivities for transition metals that are consistent with those reported in the literature...

Raman selection rule of surface optical phonon in ZnS nanobelts

KAUST Repository

Ho, Chih-Hsiang

2016-02-18

We report Raman scattering results of high-quality wurtzite ZnS nanobelts (NBs) grown by chemical vapor deposition. In Raman spectrum, the ensembles of ZnS NBs exhibit first order phonon modes at 274 cm-1 and 350 cm-1, corresponding to A1/E1 transverse optical and A1/E1 longitudinal optical phonons, in addition with strong surface optical (SO) phonon mode at 329 cm-1. The existence of SO band is confirmed by its shift with different surrounding dielectric media. Polarization dependent Raman spectrum was performed on a single ZnS NB and for the first time SO phonon band has been detected on a single nanobelt. Different selection rules of SO phonon modeshown from their corresponding E1/A1 phonon modeswere attributed to the anisotropic translational symmetry breaking on the NB surface.

Raman selection rule of surface optical phonon in ZnS nanobelts

KAUST Repository

Ho, Chih-Hsiang; Varadhan, Purushothaman; Wang, Hsin-Hua; Chen, Cheng-Ying; Fang, Xiaosheng; He, Jr-Hau

2016-01-01

We report Raman scattering results of high-quality wurtzite ZnS nanobelts (NBs) grown by chemical vapor deposition. In Raman spectrum, the ensembles of ZnS NBs exhibit first order phonon modes at 274 cm-1 and 350 cm-1, corresponding to A1/E1 transverse optical and A1/E1 longitudinal optical phonons, in addition with strong surface optical (SO) phonon mode at 329 cm-1. The existence of SO band is confirmed by its shift with different surrounding dielectric media. Polarization dependent Raman spectrum was performed on a single ZnS NB and for the first time SO phonon band has been detected on a single nanobelt. Different selection rules of SO phonon modeshown from their corresponding E1/A1 phonon modeswere attributed to the anisotropic translational symmetry breaking on the NB surface.

Evolution of Near-Surface Internal and External Oxide Morphology During High-Temperature Selective Oxidation of Steels

Science.gov (United States)

Story, Mary E.; Webler, Bryan A.

2018-05-01

In this work we examine some observations made using high-temperature confocal scanning laser microscopy (HT-CSLM) during selective oxidation experiments. A plain carbon steel and advanced high-strength steel (AHSS) were selectively oxidized at high temperature (850-900°C) in either low oxygen or water vapor atmospheres. Surface evolution, including thermal grooving along grain boundaries and oxide growth, was viewed in situ during heating. Experiments investigated the influence of the microstructure and oxidizing atmosphere on selective oxidation behavior. Sequences of CSLM still frames collected during the experiment were processed with ImageJ to obtain histograms that showed a general darkening trend indicative of oxidation over time with all samples. Additional ex situ scanning electron microscopy and energy dispersive spectroscopy analysis supported in situ observations. Distinct oxidation behavior was observed for each case. Segregation, grain orientation, and extent of internal oxidation were all found to strongly influence surface evolution.

Tunable antenna radome based on graphene frequency selective surface

Science.gov (United States)

Qu, Meijun; Rao, Menglou; Li, Shufang; Deng, Li

2017-09-01

In this paper, a graphene-based frequency selective surface (FSS) is proposed. The proposed FSS exhibits a tunable bandpass filtering characteristic due to the alterable conductivity of the graphene strips which is controlled by chemical potential. Based on the reconfigurable bandpass property of the proposed FSS, a cylindrical antenna radome is designed using the FSS unit cells. A conventional omnidirectional dipole can realize a two-beam directional pattern when it is placed into the proposed antenna radome. Forward and backward endfire radiations of the dipole loaded with the radome is realized by properly adjusting the chemical potential. The proposed antenna radome is extremely promising for beam-scanning in terahertz and mid-infrared plasmonic devices and systems when the gain of a conventional antenna needs to be enhanced.

Unraveling the role of support surface hydroxyls and its effect on the selectivity of C{sub 2} species over Rh/γ-Al{sub 2}O{sub 3} catalyst in syngas conversion: A theoretical study

Energy Technology Data Exchange (ETDEWEB)

Zhang, Riguang; Duan, Tian; Wang, Baojun, E-mail: wangbaojun@tyut.edu.cn; Ling, Lixia

2016-08-30

Highlights: • The selectivity toward CH{sub x} (x = 1–3) depends on γ-Al{sub 2}O{sub 3} support and its surface properties. • Rh/γ-Al{sub 2}O{sub 3} catalyst exhibits the higher selectivity toward CH{sub x} (x = 1,2) formation from syngas. • C{sub 2} species (C{sub 2}H{sub 2},CHCO,CH{sub 2}CHO) are the main products on Rh/γ-Al{sub 2}O{sub 3} catalyst. • γ-Al{sub 2}O{sub 3} surface hydroxyls affect the selectivity of C{sub 2} species over Rh/γ-Al{sub 2}O{sub 3} catalyst. - Abstract: The supported Rh-based catalysts exhibit the excellent catalytic performances for syngas conversion to C{sub 2} species. In this study, all possible elementary steps leading to C{sub 2} species from syngas have been explored to identify the role of support and its surface hydroxyls over Rh/γ-Al{sub 2}O{sub 3} catalyst; Here, the results are obtained using density functional theory (DFT) method. Two models: Rh4 cluster supported on the dry γ-Al{sub 2}O{sub 3}(110) surface, D(Rh4), and on the hydroxylated γ-Al{sub 2}O{sub 3}(110) surface, H(Rh4), have been used to model Rh/γ-Al{sub 2}O{sub 3} catalyst. Our results show that CO prefers to be hydrogenated to CHO, subsequently, starting from CHO species, CH and CH{sub 2} species are the dominate monomers among CH{sub x}(x = 1–3) species rather than CH{sub 3} and CH{sub 3}OH on D(Rh4) and H(Rh4) surfaces, suggesting that γ-Al{sub 2}O{sub 3}-supported Rh catalyst exhibits the high selectivity towards CH{sub x} formation compared to the pure Rh catalyst. On the other hand, D(Rh4) is more favorable for C{sub 2} hydrocarbon (C{sub 2}H{sub 2}) formation, whereas H(Rh4) surface easily produces C{sub 2} hydrocarbon (C{sub 2}H{sub 2}) and C{sub 2} oxygenates (CHCO,CH{sub 2}CHO), indicating that the surface hydroxyls of support can affect the selectivity of C{sub 2} species over Rh/γ-Al{sub 2}O{sub 3} catalyst in syngas conversion. Moreover, compared to the pure Rh(111) surface, Rh/γ-Al{sub 2}O{sub 3} catalyst can achieve the

Experimental investigation on densification behavior and surface roughness of AlSi10Mg powders produced by selective laser melting

Science.gov (United States)

Wang, Lin-zhi; Wang, Sen; Wu, Jiao-jiao

2017-11-01

Effects of laser energy density (LED) on densities and surface roughness of AlSi10Mg samples processed by selective laser melting were studied. The densification behaviors of the SLM manufactured AlSi10Mg samples at different LEDs were characterized by a solid densitometer, an industrial X-ray and CT detection system. A field emission scanning electron microscope, an automatic optical measuring system, and a surface profiler were used for measurements of surface roughness. The results show that relatively high density can be obtained with the point distance of 80-105 μm and the exposure time of 140-160 μs. The LED has an important influence on the surface morphology of the forming part, too high LED may lead to balling effect, while too low LED tends to produce defects, such as porosity and microcrack, and then affect surface roughness and porosities of the parts finally.

Surface Selective Oxide Reduction During the Intercritical Annealing of Medium Mn Steel

Science.gov (United States)

Jo, Kyoung Rae; Cho, Lawrence; Oh, Jong Han; Kim, Myoung Soo; Kang, Ki Cheol; De Cooman, Bruno C.

2017-08-01

Third generation advanced high-strength steels achieve an excellent strength-ductility balance using a cost-effective alloy composition. During the continuous annealing of medium Mn steel, the formation of an external selective oxide layer of MnO has a negative impact on the coating quality after galvanizing. A procedure to reduce the selective oxide was therefore developed. It involves annealing in the temperature range of 1073 K to 1323 K (800 °C to 1050 °C) in a HNx gas atmosphere. Annealing at higher temperatures and the use of larger H2 volume fractions are shown to make the gas atmosphere reducing with respect to MnO. The reduction of the surface MnO layer was observed by SEM, GDOES, and cross-sectional TEM analysis.

Study of the effect of nano surface morphology on the stain-resistant property of ceramic tiles

International Nuclear Information System (INIS)

Pan, S P; Hung, J K; Liu, Y T

2014-01-01

In this study, six types of commercially available ceramic tiles, including nano-structured ceramic tiles and regular ceramic tiles, were selected to investigate the effect of surface morphology on their stain-resistant property. The stain-resistant efficiencies of various ceramic tiles with nano-size surface were measured in order to determine the appropriate method for testing ceramic tiles with nano-structure surface

Selective adsorption of bovine hemoglobin on functional TiO2 nano-adsorbents: surface physic-chemical properties determined adsorption activity

Science.gov (United States)

Guo, Shiguang; Zhang, Jianghua; Shao, Mingxue; Zhang, Xia; Liu, Yufeng; Xu, Junli; Meng, Hao; Han, Yide

2015-04-01

Surface functionalized nanoparticles are efficient adsorbents which have shown good potential for protein separation. In this work, we chose two different types of organic molecules, oleic acid (OA) and 3-glycidoxypropyltrimethoxy silane (GPTMS), to functionalize the surface of TiO2 nanoparticles, and we studied the effects of this modification on their surface physicochemical properties in correlation with their selective adsorption of proteins. The results showed that the surface zeta potential and the surface water wettability of the modified TiO2 were significantly changed in comparison with the original TiO2 nanoparticles. The adsorption activities of bovine hemoglobin (BHb) and bovine serum albumin (BSA) on these functionalized TiO2 samples were investigated under different conditions, including pH values, contact time, ion strength, and initial protein concentration. In comparison with the non-specific adsorption of original TiO2, however, both the OA-TiO2 and GPTMS-TiO2 exhibited increased BHb adsorption and decreased BSA adsorption at the same time. Using a binary protein mixture as the adsorption object, a higher separation factor (SF) was obtained for OA-TiO2 under optimum conditions. The different adsorption activities of BHb and BSA on the modified TiO2 were correlated with different interactions at the protein/solid interface, and the chemical force as well as the electrostatic force played an important role in the selective adsorption process.

Influence of DC plasma modification on the selected properties and the geometrical surface structure of polylactide prior to autocatalytic metallization

Energy Technology Data Exchange (ETDEWEB)

Moraczewski, Krzysztof, E-mail: kmm@ukw.edu.pl [Kazimierz Wielki University, Chodkiewicza 30, 85-064 Bydgoszcz (Poland); Rytlewski, Piotr [Kazimierz Wielki University, Chodkiewicza 30, 85-064 Bydgoszcz (Poland); Malinowski, Rafał [Institute for Engineering of Polymer Materials and Dyes, Marii Skłodowskiej-Curie 55, 87-100 Toruń (Poland); Tracz, Adam [Centre for Molecular and Macromolecular Studies of the Polish Academy of Sciences, Sienkiewicza 112, 90-363 Łódź (Poland); Żenkiewicz, Marian [Institute for Engineering of Polymer Materials and Dyes, Marii Skłodowskiej-Curie 55, 87-100 Toruń (Poland)

2015-03-01

The paper presents the results of studies to determine the applicability of plasma modification in the process of polylactide (PLA) surface preparation prior to the autocatalytic metallization. The polylactide plasma modification was carried out in an oxygen or nitrogen chemistry. The samples were tested with the following methods: scanning electron microscopy (SEM), atomic force microscopy (AFM), goniometry and electron spectrophotometry (XPS). Scanning electron microscopy and atomic force microscopy images were demonstrated. The results of surface free energy calculations, performed based on the results of the contact angle measurements have been presented. The results of the qualitative (degree of oxidation or nitridation) and quantitative analysis of the chemical composition of the polylactide surface layer have also been described. The results of the studies show that the DC plasma modification performed in the proposed condition is a suitable as a method of surface preparation for the polylactide metallization. - Highlights: • We modified polylactide surface layer with plasma generated in oxygen or nitrogen. • We tested selected properties and surface structure of modified samples. • DC plasma modification can be used to prepare the PLA surface for metallization. • For better results metallization should be preceded by sonication process.

WIND SPEED AND ATMOSPHERIC STABILITY TRENDS FOR SELECTED UNITED STATES SURFACE STATIONS

Energy Technology Data Exchange (ETDEWEB)

Buckley, R; Allen H. Weber, A

2006-11-01

Recently it has been suggested that global warming and a decrease in mean wind speeds over most land masses are related. Decreases in near surface wind speeds have been reported by previous investigators looking at records with time spans of 15 to 30 years. This study focuses on United States (US) surface stations that have little or no location change since the late 1940s or the 1950s--a time range of up to 58 years. Data were selected from 62 stations (24 of which had not changed location) and separated into ten groups for analysis. The group's annual averages of temperature, wind speed, and percentage of Pasquill-Gifford (PG) stability categories were fitted with linear least squares regression lines. The results showed that the temperatures have increased for eight of the ten groups as expected. Wind speeds have decreased for nine of the ten groups. The mean slope of the wind speed trend lines for stations within the coterminous US was -0.77 m s{sup -1} per century. The percentage frequency of occurrence for the neutral (D) PG stability category decreased, while that for the unstable (B) and the stable (F) categories increased in almost all cases except for the group of stations located in Alaska.

Spatio-selective surface modification of glass assisted by laser-induced deposition of gold nanoparticles

International Nuclear Information System (INIS)

Takahashi, Hironobu; Niidome, Yasuro; Hisanabe, Hideyuki; Kuroiwa, Keita; Kimizuka, Nobuo; Yamada, Sunao

2006-01-01

Using pulsed laser irradiation (532 nm), dodecanethiol-capped gold nanoparticles (DT-Au) were deposited on the laser-irradiated region of a hydrophobic glass substrate modified with dimethyloctadecylchlorosilane (DMOS). After removal of deposited DT-Au, the laser-deposited region on the substrate was hydrophilic, as verified by static water contact angles. X-ray photoelectron spectroscopy suggested that the naked glass surface was not exposed at the hydrophilic region. Immersion of the substrate into gold nanorod (NR) solution selectively immobilized NRs on the hydrophilic surface via electrostatic interactions, indicating that the hydrophilic region was an anionic surface. From these results, it is expected that some immobilized DMOS groups on the laser-irradiated region of the substrate were oxidized during DT-Au deposition and fragmentation of the deposited DT-Au

Combining Phage and Yeast Cell Surface Antibody Display to Identify Novel Cell Type-Selective Internalizing Human Monoclonal Antibodies.

Science.gov (United States)

Bidlingmaier, Scott; Su, Yang; Liu, Bin

2015-01-01

Using phage antibody display, large libraries can be generated and screened to identify monoclonal antibodies with affinity for target antigens. However, while library size and diversity is an advantage of the phage display method, there is limited ability to quantitatively enrich for specific binding properties such as affinity. One way of overcoming this limitation is to combine the scale of phage display selections with the flexibility and quantitativeness of FACS-based yeast surface display selections. In this chapter we describe protocols for generating yeast surface antibody display libraries using phage antibody display selection outputs as starting material and FACS-based enrichment of target antigen-binding clones from these libraries. These methods should be widely applicable for the identification of monoclonal antibodies with specific binding properties.

On the role of melt flow into the surface structure and porosity development during selective laser melting

International Nuclear Information System (INIS)

Qiu, Chunlei; Panwisawas, Chinnapat; Ward, Mark; Basoalto, Hector C.; Brooks, Jeffery W.; Attallah, Moataz M.

2015-01-01

In this study, the development of surface structure and porosity of Ti–6Al–4V samples fabricated by selective laser melting under different laser scanning speeds and powder layer thicknesses has been studied and correlated with the melt flow behaviour through both experimental and modelling approaches. The as-fabricated samples were investigated using optical microscopy (OM) and scanning electron microscopy (SEM). The interaction between laser beam and powder particles was studied by both high speed imaging observation and computational fluid dynamics (CFD) calculation. It was found that at a high laser power and a fixed powder layer thickness (20 μm), the samples contain particularly low porosity when the laser scanning speeds are below 2700 mm/s. Further increase of scanning speed led to increase of porosity but not significantly. The porosity is even more sensitive to powder layer thickness with the use of thick powder layers (above 40 μm) leading to significant porosity. The increase of porosity with laser scanning speed and powder layer thickness is not inconsistent with the observed increase in surface roughness complicated by increasingly irregular-shaped laser scanned tracks and an increased number of discontinuity and cave-like pores on the top surfaces. The formation of pores and development of rough surfaces were found by both high speed imaging and modelling, to be strongly associated with unstable melt flow and splashing of molten material

A Monte Carlo study of adsorption of random copolymers on random surfaces

CERN Document Server

Moghaddam, M S

2003-01-01

We study the adsorption problem of a random copolymer on a random surface in which a self-avoiding walk in three dimensions interacts with a plane defining a half-space to which the walk is confined. Each vertex of the walk is randomly labelled A with probability p sub p or B with probability 1 - p sub p , and only vertices labelled A are attracted to the surface plane. Each lattice site on the plane is also labelled either A with probability p sub s or B with probability 1 - p sub s , and only lattice sites labelled A interact with the walk. We study two variations of this model: in the first case the A-vertices of the walk interact only with the A-sites on the surface. In the second case the constraint of selective binding is removed; that is, any contact between the walk and the surface that involves an A-labelling, either from the surface or from the walk, is counted as a visit to the surface. The system is quenched in both cases, i.e. the labellings of the walk and of the surface are fixed as thermodynam...

STUDIES ON SELECTED PROPERTIES OF SURFACE LAYER OF C45 STEEL OBJECTS AFTER LASER CUTTING AND MILLING

Directory of Open Access Journals (Sweden)

Kazimierz Zaleski

2014-09-01

Full Text Available The article presents the results of studying the effects of technological parameters of milling upon surface roughness and microhardness of C45 steel objects after laser cutting. The metallographic structure formed as an effect of cutting by laser was also analyzed. The milling was performed on a FV-580a vertical machining centre. Depth of cut and feed per tooth were changed within the following range: ap = 0.09–0.18 mm and fz = 0.02–0.17 mm/tooth. To measure the surface roughness a Surtronic 3+ profile graphometer was used, whereas microhardness was measured with the use of a Leco LM 700AT microhardness tester. The surface roughness was significantly improved as a result of milling. The laser beam input and output zones were eliminated. Only a part of the layer hardened by laser cutting was removed while milling, in effect of which after milling the hardness of surface layer is much higher than hardness of the core.

Theoretical study of adsorption of organic phosphines on transition metal surfaces

Science.gov (United States)

Lou, Shujie; Jiang, Hong

2018-04-01

The adsorption properties of organic phosphines on transition metal (TM) surfaces (Fe, Co, Ni, Cu, Ru, Rh, Pd, Ag, Ir, Pt, and Au) have been studied to explore the possibility of building novel heterogeneous chiral catalytic systems based on organic phosphines. Preferred adsorption sites, adsorption energies and surface electronic structures of a selected set of typical organic phosphines adsorbed on TM surfaces are calculated with density-functional theory to obtain a systematic understanding on the nature of adsorption interactions. All organic phosphines considered are found to chemically adsorb on these TM surfaces with the atop site as the most preferred one, and the TM-P bond is formed via the lone-pair electrons of the P atom and the directly contacted TM atom. These findings imply that it is indeed possible to build heterogeneous chiral catalytic systems based on organic phosphines adsorbed on TM surfaces, which, however, requires a careful design of molecular structure of organic phosphines.

A Initio Theoretical Studies of Surfaces of Semiconductors

Science.gov (United States)

Wang, Jing

1993-01-01

The first semiconductor which we study with these techniques is the archetypal elemental semiconductor, silicon. We present the first extensive study of point defects on Si(100). We identify the principal defects and two primary mechanisms responsible for their dominance: the need to eliminate dangling bonds on the surface and the need to compensate the strain induced by topological effects. Furthermore, we present evidence that the presence of point defects on the Si(100) surface is not intrinsic to the ground state of the surface as a stress relieving mechanism but rather is due merely to thermal fluctuations. We address materials issues associated with the identification of the lowest energy surfaces of GaAs and the determination of the geometric structure of a GaAs crystallite growing freely in three dimensions. The fracture energies associated with (110), (100) and (111) interface planes are calculated and a Wulff construction indicates that an ideal stoichiometric GaAs crystal should be terminated with (110) surfaces. We investigate the more complex issues that arise on surfaces when aspects of these two semiconductors are mixed. We investigate the problem of growing GaAs on the Si(100) surface and demonstrate how and why the most fundamental properties of the resulting bulk GaAs material, such as its crystalline orientation, may depend sensitively on the interplay between growth conditions such as temperature and the properties of the Si surface. For stepped Si(100) -As, we show that the growth of As directly on top of the Si surface produces a metastable state, while the replacement of the original top Si layer leads to a lower energy configuration, with the rearrangement of the surface driven by the relaxation of stress by surface steps. Finally, we study delta -doping, where one attempts to grow a single layer of Si on a GaAs surface before continuing with the growth of bulk GaAs. We shall employ a slightly different modality of the ab initio approach. We

Surface Roughness of a 3D-Printed Ni-Cr Alloy Produced by Selective Laser Melting: Effect of Process Parameters.

Science.gov (United States)

Hong, Min-Ho; Son, Jun Sik; Kwon, Tae-Yub

2018-03-01

The selective laser melting (SLM) process parameters, which directly determine the melting behavior of the metallic powders, greatly affect the nanostructure and surface roughness of the resulting 3D object. This study investigated the effect of various laser process parameters (laser power, scan rate, and scan line spacing) on the surface roughness of a nickel-chromium (Ni-Cr) alloy that was three-dimensionally (3D) constructed using SLM. Single-line formation tests were used to determine the optimal laser power of 200 W and scan rate of 98.8 mm/s, which resulted in beads with an optimal profile. In the subsequent multi-layer formation tests, the 3D object with the smoothest surface (Ra = 1.3 μm) was fabricated at a scan line spacing of 60 μm (overlap ratio = 73%). Narrow scan line spacing (and thus large overlap ratios) was preferred over wide scan line spacing to reduce the surface roughness of the 3D body. The findings of this study suggest that the laser power, scan rate, and scan line spacing are the key factors that control the surface quality of Ni-Cr alloys produced by SLM.

Selective Growth and SERS Property of Gold Nanoparticles on Amorphized Silicon Surface

International Nuclear Information System (INIS)

Matsuoka, T; Nishi, M; Sakakura, M; Shimotsuma, Y; Miura, K; Hirao, K

2011-01-01

We have fabricated gold patterns on a silicon substrate by a simple three-step method using a focused ion beam (FIB). The obtained gold patterns consisted of a large number of gold nanoparticles which grew selectively on the preprocessed silicon surface from an Au ion-containing solution dropped on the substrate. The solution was prepared by reacting HAuCl 4 aqueous solution with (3-mercaptopropyl)trimethoxysilane (MPTMS). It was found that the size and shape of the precipitating gold nanoparticles is controllable by changing the mixing ratio between HAuCl 4 aqueous solution and MPTMS. Additionally, we confirmed that the fabricated gold structures were surface enhanced Raman scattering (SERS)-active; the enhanced Raman peaks of rhodamin 6G (R6G) were detected on the fabricated gold structures, whereas no peak was detected on the alternative silicon surface. We also demonstrated the gold patterning using a femtosecond laser instead of an FIB. We believe that our method is a favorable candidate for fabricating SERS-active substrates, since the substrates can be prepared very simply and flexibly.

Selective cell culture on UV transparent polymer by F2 laser surface modification

International Nuclear Information System (INIS)

Hanada, Yasutaka; Sugioka, Koji; Kawano, Hiroyuki; Tsuchimoto, Takayoshi; Miyamoto, Iwao; Miyawaki, Atsushi; Midorikawa, Katsumi

2009-01-01

A microchip made of UV transparent polymer (CYTOP) that can perform selective cell culture has been fabricated by F 2 laser surface modification. The refractive index of CYTOP is almost the same as that of culture medium, which is essential for three-dimensional (3D) observation of cells. The F 2 laser modification of CYTOP achieves hydrophilicity only on the laser irradiated area with little deterioration of the optical properties and surface smoothness. After the laser modification, HeLa cells were successfully cultured and strongly adhered only on the modified area of CYTOP. The cells patterned on CYTOP were applied for clear 3D observation using an optical microscope in phase contrast mode.

Nonlinear optical studies of surfaces

International Nuclear Information System (INIS)

Shen, Y.R.

1994-07-01

The possibly of using nonlinear optical processes for surface studies has attracted increasing attention in recent years. Optical second harmonic generation (SHG) and sum frequency generation (SFG), in particular, have been well accepted as viable surface probes. They have many advantages over the conventional techniques. By nature, they are highly surface-specific and has a submonolayer sensitivity. As coherent optical processes, they are capable of in-situ probing of surfaces in hostile environment as well as applicable to all interfaces accessible by light. With ultrafast pump laser pulses, they can be employed to study surface dynamic processes with a subpicosecond time resolution. These advantages have opened the door to many exciting research opportunities in surface science and technology. This paper gives a brief overview of this fast-growing new area of research. Optical SHG from a surface was first studied theoretically and experimentally in the sixties. Even the submonolayer surface sensitivity of the process was noticed fairly early. The success was, however, limited because of difficulties in controlling the experimental conditions. It was not until the early 1980's that the potential of the process for surface analysis was duly recognized. The first surface study by SHG was actually motivated by the then active search for an understanding of the intriguing surface enhanced Raman scattering (SERS). It had been suspected that the enhancement in SERS mainly came from the local-field enhancement due to local plasmon resonances and pointing rod effect on rough metal surfaces. In our view, Raman scattering is a two-photon process and is therefore a nonlinear optical effect

Nanoparticle array based optical frequency selective surfaces: theory and design.

Science.gov (United States)

Saeidi, Chiya; van der Weide, Daniel

2013-07-01

We demonstrate a synthesis procedure for designing a bandstop optical frequency selective surface (FSS) composed of nanoparticle (NP) elements. The proposed FSS uses two-dimensional (2-D) periodic arrays of NPs with subwavelength unit-cell dimensions. We derive equivalent circuit for a nanoparticle array (NPA) using the closed-form solution for a 2-D NPA excited by a plane wave in the limit of the dipole approximation, which includes contribution from both individual and collective plasmon modes. Using the extracted equivalent circuit, we demonstrate synthesis of an optical FSS using cascaded NPA layers as coupled resonators, which we validate with both circuit model and full-wave simulation for a third-order Butterworth bandstop prototype.

Chemometric Analysis of Selected Organic Contaminants in Surface Water of Langat River Basin

International Nuclear Information System (INIS)

Mohamad Rafaie Mohamed Zubir; Rozita Osman; Norashikin Saim

2016-01-01

Chemometric techniques namely hierarchical agglomerative cluster analysis (HACA), discriminant analysis (DA), principal component analysis (PCA) and factor analysis (FA) were applied to the distribution of selected organic contaminants (polycyclic aromatic hydrocarbons (PAHs), sterols, pesticides (chloropyrifos), and phenol) to assess the potential of using these organic contaminants as chemical markers in Langat River Basin. Water samples were collected from February 2012 to January 2013 on a monthly basis for nine monitoring sites along Langat River Basin. HACA was able to classify the sampling sites into three clusters which can be correlated to the level of contamination (low, moderate and high contamination sites). DA was used to discriminate the sources of contamination using the selected organic contaminants and relate to the existing DOE local activities groupings. Forward and backward stepwise DA was able to discriminate two and five organic contaminants variables, respectively, from the original 13 selected variables. The five significant variables identified using backward stepwise DA were fluorene, pyrene, stigmastanol, stigmasterol and phenol. PCA and FA (varimax functionality) were used to identify the possible sources of each organic contaminant based on the inventory of local activities. Five principal components were obtained with 66.5 % of the total variation. Result from FA indicated that PAHs (pyrene, fluorene, acenaphthene, benzo[a]anthracene) originated from industrial activity and socio-economic activities; while sterols (coprostanol, stigmastanol and stigmasterol) were associated to domestic sewage and local socio-economic activities. The occurrence of chloropyrifos was correlated to agricultural activities, urban and domestic discharges. This study showed that the application of chemometrics on the distribution of selected organic contaminants was able to trace the sources of contamination in surface water. (author)

Molecular Components of Catalytic Selectivity

Energy Technology Data Exchange (ETDEWEB)

Somorjai, Gabor A.; Park, Jeong Y.

2008-07-02

Selectivity, that is, to produce one molecule out of many other thermodynamically feasible product molecules, is the key concept to develop 'clean manufacturing' processes that do not produce byproducts (green chemistry). Small differences in potential energy barriers for elementary reaction steps control which reaction channel is more likely to yield the desired product molecule (selectivity), instead of the overall activation energy for the reaction that controls turnover rates (activity). Recent studies have demonstrated the atomic- or molecular-level tailoring of parameters such as the surface structures of active sites that give rise to nanoparticle size and shape dependence of turnover rates and reaction selectivities. Here, we highlight seven molecular components that influence reaction selectivities. These include: surface structure, adsorbate-induced restructuring, adsorbate mobility, reaction intermediates, surface composition, charge transport, and oxidation states for model metal single crystal and colloid nanoparticle catalysts. We show examples of their functioning and describe in-situ instruments that permit us to investigate their roles in surface reactions.

Sn surface-enriched Pt-Sn bimetallic nanoparticles as a selective and stable catalyst for propane dehydrogenation

KAUST Repository

Zhu, Haibo

2014-12-01

A new one pot, surfactant-free, synthetic route based on the surface organometallic chemistry (SOMC) concept has been developed for the synthesis of Sn surface-enriched Pt-Sn nanoparticles. Bu3SnH selectively reacts with [Pt]-H formed in situ at the surface of Pt nanoparticles, Pt NPs, obtained by reduction of K2PtCl4 by LiB(C2H5)3H. Chemical analysis, 1H MAS and 13C CP/MAS solid-state NMR as well as two-dimensional double-quantum (DQ) and triple-quantum (TQ) experiments show that organo-tin moieties Sn(n-C4H9) are chemically linked to the surface of Pt NPs to produce, in fine, after removal of most of the n-butyl fragment, bimetallic Pt-Sn nanoparticles. The Sn(n-CH2CH2CH2CH3) groups remaining at the surface are believed to stabilize the as-synthesized Pt-Sn NPs, enabling the bimetallic NPs to be well dispersed in THF. Additionally, the Pt-Sn nanoparticles can be supported on MgAl2O4 during the synthesis of the nanoparticles. Some of the Pt-Sn/MgAl2O4 catalyst thus prepared exhibits high activity in PROX of CO and an extremely high selectivity and stability in propane dehydrogenation to propylene. The enhanced activity in propane dehydrogenation is associated with the high concentration of inactive Sn at the surface of Pt nanoparticles which ”isolates” the active Pt atoms. This conclusion is confirmed by XRD, NMR, TEM, and XPS analysis.

M13 Bacteriophage/Silver Nanowire Surface-Enhanced Raman Scattering Sensor for Sensitive and Selective Pesticide Detection.

Science.gov (United States)

Koh, Eun Hye; Mun, ChaeWon; Kim, ChunTae; Park, Sung-Gyu; Choi, Eun Jung; Kim, Sun Ho; Dang, Jaejeung; Choo, Jaebum; Oh, Jin-Woo; Kim, Dong-Ho; Jung, Ho Sang

2018-03-28

A surface-enhanced Raman scattering (SERS) sensor comprising silver nanowires (AgNWs) and genetically engineered M13 bacteriophages expressing a tryptophan-histidine-tryptophan (WHW) peptide sequence (BPWHW) was fabricated by simple mixing of BPWHW and AgNW solutions, followed by vacuum filtration onto a glass-fiber filter paper (GFFP) membrane. The AgNWs stacked on the GFFP formed a high density of SERS-active hot spots at the points of nanowire intersections, and the surface-coated BPWHW functioned as a bioreceptor for selective pesticide detection. The BPWHW-functionalized AgNW (BPWHW/AgNW) sensor was characterized by scanning electron microscopy, confocal scanning fluorescence microscopy, atomic force microscopy, and Fourier transform infrared spectroscopy. The Raman signal enhancement and the selective pesticide SERS detection properties of the BPWHW/AgNW sensor were investigated in the presence of control substrates such as wild-type M13 bacteriophage-decorated AgNWs (BPWT/AgNW) and undecorated AgNWs (AgNW). The BPWHW/AgNW sensor exhibited a significantly higher capture capability for pesticides, especially paraquat (PQ), than the control SERS substrates, and it also showed a relatively higher selectivity for PQ than for other bipyridylium pesticides such as diquat and difenzoquat. Furthermore, as a field application test, PQ was detected on the surface of PQ-pretreated apple peels, and the results demonstrated the feasibility of using a paper-based SERS substrate for on-site residual pesticide detection. The developed M13 bacteriophage-functionalized AgNW SERS sensor might be applicable for the detection of various pesticides and chemicals through modification of the M13 bacteriophage surface peptide sequence.

A surface acoustic wave sensor functionalized with a polypyrrole molecularly imprinted polymer for selective dopamine detection.

Science.gov (United States)

Maouche, Naima; Ktari, Nadia; Bakas, Idriss; Fourati, Najla; Zerrouki, Chouki; Seydou, Mahamadou; Maurel, François; Chehimi, Mohammed Mehdi

2015-11-01

A surface acoustic wave sensor operating at 104 MHz and functionalized with a polypyrrole molecularly imprinted polymer has been designed for selective detection of dopamine (DA). Optimization of pyrrole/DA ratio, polymerization and immersion times permitted to obtain a highly selective sensor, which has a sensitivity of 0.55°/mM (≈ 550 Hz/mM) and a detection limit of ≈ 10 nM. Morphology and related roughness parameters of molecularly imprinted polymer surfaces, before and after extraction of DA, as well as that of the non imprinted polymer were characterized by atomic force microscopy. The developed chemosensor selectively recognized dopamine over the structurally similar compound 4-hydroxyphenethylamine (referred as tyramine), or ascorbic acid,which co-exists with DA in body fluids at a much higher concentration. Selectivity tests were also carried out with dihydroxybenzene, for which an unexpected phase variation of order of 75% of the DA one was observed. Quantum chemical calculations, based on the density functional theory, were carried out to determine the nature of interactions between each analyte and the PPy matrix and the DA imprinted PPy polypyrrole sensing layer in order to account for the important phase variation observed during dihydroxybenzene injection. Copyright © 2015 John Wiley & Sons, Ltd.

Selective propagation and beam splitting of surface plasmons on metallic nanodisk chains.

Science.gov (United States)

Hu, Yuhui; Zhao, Di; Wang, Zhenghan; Chen, Fei; Xiong, Xiang; Peng, Ruwen; Wang, Mu

2017-05-01

Manipulating the propagation of surface plasmons (SPs) on a nanoscale is a fundamental issue of nanophotonics. By using focused electron beam, SPs can be excited with high spatial accuracy. Here we report on the propagation of SPs on a chain of gold nanodisks with cathodoluminescence (CL) spectroscopy. Experimental evidence for the propagation of SPs excited by the focused electron beam is demonstrated. The wavelength of the transmitted SPs depends on the geometrical parameters of the nanodisk chain. Furthermore, we design and fabricate a beam splitter, which selectively transmits SPs of certain wavelengths to a specific direction. By scanning the sample surface point by point and collecting the CL spectra, we obtain the spectral mapping and identify that the chain of the smaller nanodisks can efficiently transport SPs at shorter wavelengths. This Letter provides a unique approach to manipulate in-plane propagation of SPs.

Surface Quality Research for Selective Laser Melting of Ti-6Al-4V Alloy

Directory of Open Access Journals (Sweden)

Król M.

2016-09-01

Full Text Available One of the innovative technology of producing the components is Selective Laser Melting (SLM belongs to additive manufacturing techniques. SLM technology has already been successfully applied in the automotive, aerospace and medical industries. Despite progress in material flexibility and mechanical performances, relatively poor surface finish still presents a significant weakness in the SLM process.

Dimensional Accuracy and Surface Roughness Analysis for AlSi10Mg Produced by Selective Laser Melting (SLM

Directory of Open Access Journals (Sweden)

Kamarudin K.

2016-01-01

Full Text Available Selective Laser Melting (SLM is an Additive Manufacturing (AM technique that built 3D part in a layer-by-layer method by melting the top surface layer of a powder bed with a high intensity laser according to sliced 3D CAD data. AlSi10Mg alloy is a traditional cast alloy that is broadly used for die-casting process and used in automotive industry due its good mechanical properties. This paper seeks to investigate the requirement SLM in rapid tooling application. The feasibility study is done by examining the surface roughness and dimensional accuracy as compared to the benchmark part produced through the SLM process with constant parameters. The benchmark produced by SLM shows the potential of SLM in a manufacturing application particularly in moulds.

Selective adsorption of oppositely charged PNIPAAM on halloysite surfaces: a route to thermo-responsive nanocarriers.

Science.gov (United States)

Cavallaro, Giuseppe; Lazzara, Giuseppe; Lisuzzo, Lorenzo; Milioto, Stefana; Parisi, Filippo

2018-05-17

Halloysite nanotubes were functionalized with stimuli-responsive macromolecules to generate smart nanohybrids. Poly(N-isopropylacrylamide)-co-methacrylic acid (PNIPAAM-co-MA) was selectively adsorbed into halloysite lumen by exploiting electrostatic interactions. Amine-terminated PNIPAAM polymer was also investigated that selectively interacts with the outer surface of the nanotubes. The adsorption site has a profound effect on the thermodynamic behavior and therefore temperature responsive features of the hybrid material. The drug release kinetics was investigated by using Diclofenac as a non-steroidal anti-inflammatory drug model. The release kinetics depends on the nanoarchitecture of the PNIPAAM/Halloysite based material. In particular, diclofenac release was slowed down above the LCST for PNIPAAM-co-MA/Halloysite. Opposite trends occurred for Halloysite functionalized with PNIPAAM at the outer surface. This work represents a further step toward the opportunity to extend and control the delivery conditions of active species, which represent a key point in technological applications. © 2018 IOP Publishing Ltd.

Surface-modified CdS nanoparticles as a fluorescent probe for the selective detection of cysteine

International Nuclear Information System (INIS)

Negi, Devendra P S; Chanu, T Inakhunbi

2008-01-01

We present a novel method for the selective detection of cysteine, a sulfur-containing amino acid, which plays a crucial role in many important biological functions such as protein folding. Surface-modified colloidal CdS nanoparticles have been used as a fluorescent probe to selectively detect cysteine in the presence of other amino acids in the micromolar concentration range. Cysteine quenches the emission of CdS in the 0.5-10 μM concentration range, whereas the other amino acids do not affect its emission. Among the other amino acids, histidine is most efficient in quenching the emission of the CdS nanoparticles. The sulfur atom of cysteine plays a crucial role in the quenching process in the 0.5-10 μM concentration range. Cysteine is believed to quench the emission of the CdS nanoparticles by binding to their surface via its negatively charged sulfur atom. This method can potentially be applied for its detection in biological samples.

Generation of radio vortex beams with designable polarization using anisotropic frequency selective surface

Science.gov (United States)

Yang, Jin; Zhang, Cheng; Ma, Hui Feng; Zhao, Jie; Dai, Jun Yan; Yuan, Wei; Yang, Liu Xi; Cheng, Qiang; Cui, Tie Jun

2018-05-01

We propose a strategy to convert a linearly polarized wave from a single point source to an orbital angular momentum (OAM) wave by arbitrary polarization via an anisotropic frequency selective surface (FSS) in the microwave frequency. By tailoring the geometries of FSS elements, reflection-phases in x and y polarizations are engineered and encoded independently, which allows us to design the eventual polarization state of the generated OAM vortex beam by elaborately selecting individual coding sequences for each polarization. Two types of FSSs are designed and experimentally characterized to demonstrate the capability of OAM generation with circular and linear polarizations, respectively, showing excellent performance in a wide bandwidth from 14 to 16 GHz. This method provides opportunities for polarization multiplexing in microwave OAM communication systems.

Linear and nonlinear surface spectroscopy of supported size selected metal clusters and organic adsorbates

Energy Technology Data Exchange (ETDEWEB)

Thaemer, Martin Georg

2012-03-08

The spectroscopic investigation of supported size selected metal clusters over a wide wavelength range plays an important role for understanding their outstanding catalytic properties. The challenge which must be overcome to perform such measurements is the difficult detection of the weak spectroscopic signals from these samples. As a consequence, highly sensitive spectroscopic methods are applied, such as surface Cavity Ringdown Spectroscopy and surface Second Harmonic Generation Spectroscopy. The spectroscopic apparatus developed is shown to have a sensitivity which is high enough to detect sub-monolayer coverages of adsorbates on surfaces. In the measured spectra of small supported silver clusters of the sizes Ag{sub 4}2, Ag{sub 2}1, Ag{sub 9}, and Ag atoms a stepwise transition from particles with purely metallic character to particles with molecule-like properties can be observed within this size range.

Thermodynamic and kinetic aspects on the selective surface oxidation of binary, ternary and quarternary model alloys

International Nuclear Information System (INIS)

Swaminathan, Srinivasan; Spiegel, Michael

2007-01-01

Segregation and selective oxidation phenomena of minor alloying elements during annealing of steel sheets lead to the formation of bare spots after hot dip galvanizing. In order to understand the influence of common alloying elements on the surface chemistry after annealing, model alloys of binary (Fe-2Si, Fe-2Mn and Fe-0.8Cr), ternary (Fe-2Mn-2Si, Fe-2Mn-0.8Cr and Fe-2Si-0.8Cr) and quarternary (Fe-2Mn-2Si-0.8Cr) systems were investigated. The specimens were annealed for 60 s at 820 deg. C in N 2 -5% H 2 gas atmospheres with different dew points -80 and -40 deg. C, respectively. Surface chemistry of the annealed specimens was obtained by using X-ray photoelectron spectroscopy (XPS). The field emission scanning electron microscopy (FE-SEM) was used to view surface morphology. At low dew point -80 deg. C, apart from the thermodynamical calculations such as solubility product of oxides and their critical solute concentrations, kinetics play a decisive role on the selective oxidation, i.e. oxygen competition. As expected, the amount of external selective oxidation of alloying elements are well pronounced at higher dew point -40 deg. C. An attempt has been made to explain the dominant process of Si and Mn on Cr-oxidation and segregation. It is observed that annealing of quarternary system at higher dew point shifts the Cr-oxidation from external to internal

Thermodynamic and kinetic aspects on the selective surface oxidation of binary, ternary and quarternary model alloys

Energy Technology Data Exchange (ETDEWEB)

Swaminathan, Srinivasan [High Temperature Reactions Group, Department of Interface Chemistry and Surface Engineering, Max-Planck-Institut fuer Eisenforschung GmbH, Max-Planck-Str. 1, D-40237 Duesseldorf (Germany)]. E-mail: s.swaminathan@mpie.de; Spiegel, Michael [High Temperature Reactions Group, Department of Interface Chemistry and Surface Engineering, Max-Planck-Institut fuer Eisenforschung GmbH, Max-Planck-Str. 1, D-40237 Duesseldorf (Germany)

2007-03-15

Segregation and selective oxidation phenomena of minor alloying elements during annealing of steel sheets lead to the formation of bare spots after hot dip galvanizing. In order to understand the influence of common alloying elements on the surface chemistry after annealing, model alloys of binary (Fe-2Si, Fe-2Mn and Fe-0.8Cr), ternary (Fe-2Mn-2Si, Fe-2Mn-0.8Cr and Fe-2Si-0.8Cr) and quarternary (Fe-2Mn-2Si-0.8Cr) systems were investigated. The specimens were annealed for 60 s at 820 deg. C in N{sub 2}-5% H{sub 2} gas atmospheres with different dew points -80 and -40 deg. C, respectively. Surface chemistry of the annealed specimens was obtained by using X-ray photoelectron spectroscopy (XPS). The field emission scanning electron microscopy (FE-SEM) was used to view surface morphology. At low dew point -80 deg. C, apart from the thermodynamical calculations such as solubility product of oxides and their critical solute concentrations, kinetics play a decisive role on the selective oxidation, i.e. oxygen competition. As expected, the amount of external selective oxidation of alloying elements are well pronounced at higher dew point -40 deg. C. An attempt has been made to explain the dominant process of Si and Mn on Cr-oxidation and segregation. It is observed that annealing of quarternary system at higher dew point shifts the Cr-oxidation from external to internal.

Absolute Molecular Orientation of Isopropanol at Ceria (100) Surfaces: Insight into Catalytic Selectivity from the Interfacial Structure

Energy Technology Data Exchange (ETDEWEB)

Doughty, Benjamin [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Goverapet Srinivasan, Sriram [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Indian Inst. of Technology (IIT), Rajasthan (India); Bryantsev, Vyacheslav S. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Lee, Dongkyu [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Lee, Ho Nyung [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Ma, Ying-Zhong [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Lutterman, Daniel A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2017-06-12

The initial mechanistic steps underlying heterogeneous chemical catalysis can be described in a framework where the composition, structure, and orientation of molecules adsorbed to reactive interfaces are known. However, extracting this vital information is the limiting step in most cases due in part to challenges in probing the interfacial monolayer with enough chemical specificity to characterize the surface molecular constituents. These challenges are exacerbated at complex or spatially heterogeneous interfaces where competing processes and a distribution of local environments can uniquely drive chemistry. To address these limitations, this work presents a distinctive combination of materials synthesis, surface specific optical experiments, and theory to probe and understand molecular structure at catalytic interfaces. Specifically, isopropanol was adsorbed to surfaces of the model CeO₂ catalyst that were synthesized with only the (100) facet exposed. Vibrational sum-frequency generation was used to probe the molecular monolayer, and with the guidance of density functional theory calculations, was used to extract the structure and absolute molecular orientation of isopropanol at the CeO₂ (100) surface. Our results show that isopropanol is readily deprotonated at the surface, and through the measured absolute molecular orientation of isopropanol, we obtain new insight into the selectivity of the (100) surface to form propylene. Our findings reveal key insight into the chemical and physical phenomena taking place at pristine interfaces thereby pointing to intuitive structural arguments to describe catalytic selectivity in more complex systems.

Nonlinear optical techniques for surface studies

International Nuclear Information System (INIS)

Shen, Y.R.

1981-09-01

Recent effort in developing nonlinear optical techniques for surface studies is reviewed. Emphasis is on monolayer detection of adsorbed molecules on surfaces. It is shown that surface coherent antiStokes Raman scattering (CARS) with picosecond pulses has the sensitivity of detecting submonolayer of molecules. On the other hand, second harmonic or sum-frequency generation is also sensitive enough to detect molecular monolayers. Surface-enhanced nonlinear optical effects on some rough metal surfaces have been observed. This facilitates the detection of molecular monolayers on such surfaces, and makes the study of molecular adsorption at a liquid-metal interface feasible. Advantages and disadvantages of the nonlinear optical techniques for surface studies are discussed

Mirror reactor surface study

Energy Technology Data Exchange (ETDEWEB)

Hunt, A. L.; Damm, C. C.; Futch, A. H.; Hiskes, J. R.; Meisenheimer, R. G.; Moir, R. W.; Simonen, T. C.; Stallard, B. W.; Taylor, C. E.

1976-09-01

A general survey is presented of surface-related phenomena associated with the following mirror reactor elements: plasma first wall, ion sources, neutral beams, director converters, vacuum systems, and plasma diagnostics. A discussion of surface phenomena in possible abnormal reactor operation is included. Several studies which appear to merit immediate attention and which are essential to the development of mirror reactors are abstracted from the list of recommended areas for surface work. The appendix contains a discussion of the fundamentals of particle/surface interactions. The interactions surveyed are backscattering, thermal desorption, sputtering, diffusion, particle ranges in solids, and surface spectroscopic methods. A bibliography lists references in a number of categories pertinent to mirror reactors. Several complete published and unpublished reports on surface aspects of current mirror plasma experiments and reactor developments are also included.

Mirror reactor surface study

International Nuclear Information System (INIS)

Hunt, A.L.; Damm, C.C.; Futch, A.H.; Hiskes, J.R.; Meisenheimer, R.G.; Moir, R.W.; Simonen, T.C.; Stallard, B.W.; Taylor, C.E.

1976-01-01

A general survey is presented of surface-related phenomena associated with the following mirror reactor elements: plasma first wall, ion sources, neutral beams, director converters, vacuum systems, and plasma diagnostics. A discussion of surface phenomena in possible abnormal reactor operation is included. Several studies which appear to merit immediate attention and which are essential to the development of mirror reactors are abstracted from the list of recommended areas for surface work. The appendix contains a discussion of the fundamentals of particle/surface interactions. The interactions surveyed are backscattering, thermal desorption, sputtering, diffusion, particle ranges in solids, and surface spectroscopic methods. A bibliography lists references in a number of categories pertinent to mirror reactors. Several complete published and unpublished reports on surface aspects of current mirror plasma experiments and reactor developments are also included

Betsy Pugel, Tiny houses: Planetary protection-focused materials selection for spaceflight hardware surfaces

OpenAIRE

Schriml, Lynn

2017-01-01

Betsy Pugel, National Aeronautics and Space Administration Tiny houses: Planetary protection-focused materials selection for spaceflight hardware surfacesOn October 10-12th, 2017 the Alfred P. Sloan Foundation and The National Academies of Sciences, Engineering and Medicine co-hosting MoBE 2017 (Microbiology of the Built Environment Research and Applications Symposium) at the National Academy of Sciences Building to present the current state-of-the-science in understanding the formation and ...

Crystal structure and nanotopographical features on the surface of heat-treated and anodized porous titanium biomaterials produced using selective laser melting

Energy Technology Data Exchange (ETDEWEB)

Amin Yavari, S., E-mail: s.aminyavari@tudelft.nl [Faculty of Mechanical, Maritime, and Materials Engineering, Delft University of Technology (TU Delft), Mekelweg 2, 2628 CD Delft (Netherlands); FT Innovations BV, Braamsluiper 1, 5831 PW Boxmeer (Netherlands); Wauthle, R. [KU Leuven, Department of Mechanical Engineering, Section Production Engineering, Machine Design and Automation (PMA), Celestijnenlaan 300B, 3001 Leuven (Belgium); LayerWise NV, Kapeldreef 60, Leuven (Belgium); Böttger, A.J. [Faculty of Mechanical, Maritime, and Materials Engineering, Delft University of Technology (TU Delft), Mekelweg 2, 2628 CD Delft (Netherlands); Schrooten, J. [Department of Metallurgy and Materials Engineering, KU Leuven, Kasteelpark Arenberg 44 PB 2450, 3001 Heverlee (Belgium); Weinans, H. [Faculty of Mechanical, Maritime, and Materials Engineering, Delft University of Technology (TU Delft), Mekelweg 2, 2628 CD Delft (Netherlands); Department of Orthopedics and Department of Rheumatology, UMC Utrecht, Heidelberglaan 100, 3584 CX Utrecht (Netherlands); Zadpoor, A.A. [Faculty of Mechanical, Maritime, and Materials Engineering, Delft University of Technology (TU Delft), Mekelweg 2, 2628 CD Delft (Netherlands)

2014-01-30

Porous titanium biomaterials manufactured using additive manufacturing techniques such as selective laser melting are considered promising materials for orthopedic applications where the biomaterial needs to mimic the properties of bone. Despite their appropriate mechanical properties and the ample pore space they provide for bone ingrowth and osseointegration, porous titanium structures have an intrinsically bioinert surface and need to be subjected to surface bio-functionalizing procedures to enhance their in vivo performance. In this study, we used a specific anodizing process to build a hierarchical oxide layer on the surface of porous titanium structures made by selective laser melting of Ti6Al4V ELI powder. The hierarchical structure included both nanotopographical features (nanotubes) and micro-features (micropits). After anodizing, the biomaterial was heat treated in Argon at different temperatures ranging between 400 and 600 °C for either 1 or 2 h to improve its bioactivity. The effects of applied heat treatment on the crystal structure of TiO{sub 2} nanotubes and the nanotopographical features of the surface were studied using scanning electron microscopy and X-ray diffraction. It was shown that the transition from the initial crystal structure, i.e. anatase, to rutile occurs between 500 and 600 °C and that after 2 h of heat treatment at 600 °C the crystal structure is predominantly rutile. The nanotopographical features of the surface were found to be largely unchanged for heat treatments carried out at 500 °C or below, whereas they were partially or largely disrupted after heat treatment at 600 °C. The possible implications of these findings for the bioactivity of porous titanium structures are discussed.

Selective permeability of uranyl peroxide nanocages to different alkali ions: influences from surface pores and hydration shells

International Nuclear Information System (INIS)

Gao, Yunyi; Haso, Fadi; Zhou, Jing; Hu, Lang; Liu, Tianbo; Szymanowski, Jennifer E.S.; Burns, Peter C.

2015-01-01

The precise guidance to different ions across the biological channels is essential for many biological processes. An artificial nanopore system will facilitate the study of the ion-transport mechanism through nanosized channels and offer new views for designing nanodevices. Herein we reveal that a 2.5 nm-sized, fullerene-shaped molecular cluster Li_4_8_+_mK_1_2(OH)_m[UO_2(O_2)(OH)]_6_0_-(H_2O)_n (m∼20 and n∼310) (U_6_0) shows selective permeability to different alkali ions. The subnanometer pores on the water-ligand-rich surface of U_6_0 are able to block Rb"+ and Cs"+ ions from passing through, while allowing Na"+ and K"+ ions, which possess larger hydrated sizes, to enter the interior space of U_6_0. An interestingly high entropy gain during the binding process between U_6_0 and alkali ions suggests that the hydration shells of Na"+/K"+ and U_6_0 are damaged during the interaction. The ion selectivity of U_6_0 is greatly influenced by both the morphologies of the surface nanopores and the dynamics of the hydration shells. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Preparation of a surface-grafted imprinted ceramic membrane for selective separation of molybdate anion from water solutions.

Science.gov (United States)

Zeng, Jianxian; Dong, Zhihui; Zhang, Zhe; Liu, Yuan

2017-07-05

A surface-grafted imprinted ceramic membrane (IIP-PVI/CM) for recognizing molybdate (Mo(VI)) anion was prepared by surface-initiated graft-polymerization. Firstly, raw alumina ceramic membrane (CM) was deposited with SiO 2 active layer by situ hydrolysis deposition method. Subsequently, γ-methacryloxy propyl trimethoxyl silane (MPS) was used as a coupling agent to introduce double bonds onto the SiO 2 layer (MPS-CM). Then, 1-vinylimidazole (VI) was employed as a functional monomer to graft-polymerization onto the MPS-CM (PVI-CM). During the graft-polymerization, the influence factors of grafting degree of PVI were investigated in detail. Under optimum conditions (monomer concentration 20wt%, temperature 70°C, initiator amount 1.1wt% and reaction time 8h), the grafting degree of 20.39g/100g was obtained. Further, Mo(VI) anion was used as a template to imprint in the PVI-CM by employing 1,6-dibromohexane as a cross-linking agent, and then Mo(VI) was removed, obtaining the IIP-PVI/CM with many imprinted cavities for Mo(VI). Thereafter, static adsorption and dynamic separation properties of IIP-PVI/CM for Mo(VI) were studied. Results indicate that IIP-PVI/CM shows a specific selectivity for Mo(VI) with the adsorption capacity of 0.69mmol/100g, and the selectivity coefficient of IIP-PVI/CM is 7.48 for molybdate to tungstate anions. During the dynamic separation, IIP-PVI/CM has also good selectivity for separation of Mo(VI) and W(VI) anions. Copyright © 2017 Elsevier B.V. All rights reserved.

Selective binding of oligonucleotide on TiO2 surfaces modified by swift heavy ion beam lithography

International Nuclear Information System (INIS)

Vicente Pérez-Girón, J.; Hirtz, M.; McAtamney, C.; Bell, A.P.; Antonio Mas, J.; Jaafar, M.; Luis, O. de; Fuchs, H.

2014-01-01

We have used swift heavy-ion beam based lithography to create patterned bio-functional surfaces on rutile TiO 2 single crystals. The applied lithography method generates a permanent and well defined periodic structure of micrometre sized square holes having nanostructured TiO 2 surfaces, presenting different physical and chemical properties compared to the surrounding rutile single crystal surface. On the patterned substrates selective binding of oligonucleotides molecules is possible at the surfaces of the holes. This immobilisation process is only being controlled by UV light exposure. The patterned transparent substrates are compatible with fluorescence detection techniques, are mechanically robust, have a high tolerance to extreme chemical and temperature environments, and apparently do not degrade after ten cycles of use. These qualities make the patterned TiO 2 substrates useful for potential biosensor applications

The Influence of As-Built Surface Conditions on Mechanical Properties of Ti-6Al-4V Additively Manufactured by Selective Electron Beam Melting

Science.gov (United States)

Sun, Y. Y.; Gulizia, S.; Oh, C. H.; Fraser, D.; Leary, M.; Yang, Y. F.; Qian, M.

2016-03-01

Achieving a high surface finish is a major challenge for most current metal additive manufacturing processes. We report the first quantitative study of the influence of as-built surface conditions on the tensile properties of Ti-6Al-4V produced by selective electron beam melting (SEBM) in order to better understand the SEBM process. Tensile ductility was doubled along with noticeable improvements in tensile strengths after surface modification of the SEBM-fabricated Ti-6Al-4V by chemical etching. The fracture surfaces of tensile specimens with different surface conditions were characterised and correlated with the tensile properties obtained. The removal of a 650- μm-thick surface layer by chemical etching was shown to be necessary to eliminate the detrimental influence of surface defects on mechanical properties. The experimental results and analyses underline the necessity to modify the surfaces of SEBM-fabricated components for structural applications, particularly for those components which contain complex internal concave and convex surfaces and channels.

Covalent co-immobilization of heparin/laminin complex that with different concentration ratio on titanium surface for selectively direction of platelets and vascular cells behavior

International Nuclear Information System (INIS)

Wang, Jian; Chen, Yuan; Liu, Tao; Wang, Xue; Liu, Yang; Wang, Yuan; Chen, Junying; Huang, Nan

2014-01-01

Highlights: • Extracellular matrix inspired surface modification with fibronectin, heparin and VEGF to construct a favorable microenvironment for selectively anticoagulant and promote endothelialization. • Take the advantage of specific intermolecular interaction, the bioactivity of above biomolecules was more efficiently maintained in compared with the common used covalent immobilization method. • Poly-l-lysine was used as a novel interlayer for surface amination, and in comparison, PLL coating was more feasible and the degradation product had no harm to human body. - Abstract: Surface biofunctional modification of coronary artery stent to improve the hemocompatibility and selectively accelerate endothelium regeneration but prevent restenosis have been become a new hotspot. For this, a novel method was developed in this work by co-immobilization of Ln and heparin complex on poly-L-lysine modified Ti surface. Take the advantage of the specific interaction between Ln and heparin, Ln and heparin complexes with different concentration ratios were set up for creating different exposure density of these two types of biomolecules. According to biocompatibility evaluation results, the Hep/Ln complexes modified surface displayed less platelet adhesion and activation. Especially, on L(150)H and L(200)H surface, the AT III binding quantity, APTT value and anti-coagulation property of modified surface were significantly promoted. Furthermore, the adherent density and proliferation activity of ECs and EPCs were positively correlated with Ln concentration. Notably, the proliferation of both ECs and EPCs on L(100)H, L(150)H and L(200)H surface were greatly promoted. Another hand, the proliferation activity of SMCs was significantly inhibited on Hep/Ln modified surfaces, which was considered mainly due to the inhibitory effect of heparin to SMCs. According to the existing results, this study demonstrated that in a certain range of heparin and laminin concentration ratio

Preliminary Study of the Potential Extracts from Selected Plants to Improve Surface Cleaning

Directory of Open Access Journals (Sweden)

Ai Ting Vong

2018-03-01

Full Text Available Environment hygiene is important for preventing infection and promoting a healthier environment in which to live or work. The goal of this study was to examine the antimicrobial effects of Citrus aurantifolia (key lime juice and aqueous extracts of Cinnamomum iners (cinnamon bark and Citrus hystrix (kaffir lime leaves on the kinetic growth of Pseudomonas aeruginosa and methicillin resistance Staphylococcus aureus (MRSA. Antimicrobial activity was quantitatively evaluated using spectrophotometry and viable cell counts versus bacterial growth time. The fomite surface samples that were used in the second experiment were chosen randomly from the laboratories. They were assessed both before and after intervention using a mixture of commercial disinfectant detergent and lime juice. In the kinetic growth study, the lime juice effectively eliminated P. aeruginosa and MRSA. The cinnamon bark extract was more effective at inhibiting P. aeruginosa than MRSA. The kaffir lime leaf extract demonstrated bacteriostatic activity for the first 60 min, which then weakened after 90 min for both bacteria. The lime juice extract and commercial disinfectant mixture effectively disinfected the fomites. Further studies of the use of key lime juice as a disinfectant in the hospital environment should be conducted, as C. aurantifolia exhibits antibacterial activities against endemic microbes.

Analysis and applications of a frequency selective surface via a random distribution method

International Nuclear Information System (INIS)

Xie Shao-Yi; Huang Jing-Jian; Yuan Nai-Chang; Liu Li-Guo

2014-01-01

A novel frequency selective surface (FSS) for reducing radar cross section (RCS) is proposed in this paper. This FSS is based on the random distribution method, so it can be called random surface. In this paper, the stacked patches serving as periodic elements are employed for RCS reduction. Previous work has demonstrated the efficiency by utilizing the microstrip patches, especially for the reflectarray. First, the relevant theory of the method is described. Then a sample of a three-layer variable-sized stacked patch random surface with a dimension of 260 mm×260 mm is simulated, fabricated, and measured in order to demonstrate the validity of the proposed design. For the normal incidence, the 8-dB RCS reduction can be achieved both by the simulation and the measurement in 8 GHz–13 GHz. The oblique incidence of 30° is also investigated, in which the 7-dB RCS reduction can be obtained in a frequency range of 8 GHz–14 GHz. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

Selective cell culture on UV transparent polymer by F{sub 2} laser surface modification

Energy Technology Data Exchange (ETDEWEB)

Hanada, Yasutaka, E-mail: y-hanada@riken.jp [RIKEN-Advanced Science Institute, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Sugioka, Koji [RIKEN-Advanced Science Institute, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Kawano, Hiroyuki [RIKEN-Brain Science Institute, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Tsuchimoto, Takayoshi [RIKEN-Advanced Science Institute, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Department of Applied Electronics, Faculty of Industrial Science and Technology Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510 (Japan); Miyamoto, Iwao [Department of Applied Electronics, Faculty of Industrial Science and Technology Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510 (Japan); Miyawaki, Atsushi [RIKEN-Brain Science Institute, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Midorikawa, Katsumi [RIKEN-Advanced Science Institute, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan)

2009-09-30

A microchip made of UV transparent polymer (CYTOP) that can perform selective cell culture has been fabricated by F{sub 2} laser surface modification. The refractive index of CYTOP is almost the same as that of culture medium, which is essential for three-dimensional (3D) observation of cells. The F{sub 2} laser modification of CYTOP achieves hydrophilicity only on the laser irradiated area with little deterioration of the optical properties and surface smoothness. After the laser modification, HeLa cells were successfully cultured and strongly adhered only on the modified area of CYTOP. The cells patterned on CYTOP were applied for clear 3D observation using an optical microscope in phase contrast mode.

First-principles study of low Miller index Ni3S2 surfaces in hydrotreating conditions.

Science.gov (United States)

Aray, Yosslen; Vega, David; Rodriguez, Jesus; Vidal, Alba B; Grillo, Maria Elena; Coll, Santiago

2009-03-12

Density functional theory (DFT) calculations combined with surface thermodynamic arguments and the Gibbs-Curie-Wulff equilibrium morphology formalism have been employed to explore the effect of the reaction conditions, temperature (T), and gas-phase partial pressures (PH2 and PH2S) on the stability of nickel sulfide (Ni3S2) surfaces. Furthermore, the strength and nature of chemical bonds for selected Ni3S2 surface cuts were investigated with the quantum theory of atoms in molecules methodology. A particular analysis of the electrostatic potential within this theoretical framework is performed to study the potential activity of nickel sulfide nanoparticles as hydrodesulfurization (HDS) catalysts. The calculated thermodynamic surface stabilities and the resulting equilibrium morphology model suggest that unsupported Ni3S2 nanoparticles mainly expose (111) and (111) type surface faces in HDS conditions. Analysis of the electrostatic potential mapped onto a selected electron density isocontour (0.001 au) on those expose surface reveals a poor potential reactivity toward electron-donating reagents (i.e., low Lewis acidity). Consequently, a very low attraction between coordinatively unsaturated active sites (Lewis sites) exposed at the catalytic particles and the S atoms coming from reagent polluting molecules does inactive these kinds of particles for HDS.

Major membrane surface proteins of Mycoplasma hyopneumoniae selectively modified by covalently bound lipid

International Nuclear Information System (INIS)

Wise, K.S.; Kim, M.F.

1987-01-01

Surface protein antigens of Mycoplasma hyopneumoniae were identified by direct antibody-surface binding or by radioimmunoprecipitation of surface 125 I-labeled proteins with a series of monoclonal antibodies (MAbs). Radioimmunoprecipitation of TX-114-phase proteins from cells labeled with [ 35 S] methionine, 14 C-amino acids, or [ 3 H] palmitic acid showed that proteins p65, p50, and p44 were abundant and (with one other hydrophobic protein, p60) were selectively labeled with lipid. Alkaline hydroxylamine treatment of labeled proteins indicated linkage of lipids by amide or stable O-linked ester bonds. Proteins p65, p50, and p44 were highly immunogenic in the natural host as measured by immunoblots of TX-114-phase proteins with antisera from swine inoculated with whole organisms. These proteins were antigenically and structurally unrelated, since hyperimmune mouse antibodies to individual gel-purified proteins were monospecific and gave distinct proteolytic epitope maps. Intraspecies size variants of one surface antigen of M. hyopneumoniae were revealed by a MAb to p70 (defined in strain J, ATCC 25934), which recognized a large p73 component on strain VPP11 (ATCC 25617). In addition, MAb to internal, aqueous-phase protein p82 of strain J failed to bind an analogous antigen in strain VPP11

Major membrane surface proteins of Mycoplasma hyopneumoniae selectively modified by covalently bound lipid

Energy Technology Data Exchange (ETDEWEB)

Wise K.S.; Kim, M.F.

1987-12-01

Surface protein antigens of Mycoplasma hyopneumoniae were identified by direct antibody-surface binding or by radioimmunoprecipitation of surface /sup 125/I-labeled proteins with a series of monoclonal antibodies (MAbs). Radioimmunoprecipitation of TX-114-phase proteins from cells labeled with (/sup 35/S) methionine, /sup 14/C-amino acids, or (/sup 3/H) palmitic acid showed that proteins p65, p50, and p44 were abundant and (with one other hydrophobic protein, p60) were selectively labeled with lipid. Alkaline hydroxylamine treatment of labeled proteins indicated linkage of lipids by amide or stable O-linked ester bonds. Proteins p65, p50, and p44 were highly immunogenic in the natural host as measured by immunoblots of TX-114-phase proteins with antisera from swine inoculated with whole organisms. These proteins were antigenically and structurally unrelated, since hyperimmune mouse antibodies to individual gel-purified proteins were monospecific and gave distinct proteolytic epitope maps. Intraspecies size variants of one surface antigen of M. hyopneumoniae were revealed by a MAb to p70 (defined in strain J, ATCC 25934), which recognized a large p73 component on strain VPP11 (ATCC 25617). In addition, MAb to internal, aqueous-phase protein p82 of strain J failed to bind an analogous antigen in strain VPP11.

A highly selective and self-powered gas sensor via organic surface functionalization of p-Si/n-ZnO diodes.

Science.gov (United States)

Hoffmann, Martin W G; Mayrhofer, Leonhard; Casals, Olga; Caccamo, Lorenzo; Hernandez-Ramirez, Francisco; Lilienkamp, Gerhard; Daum, Winfried; Moseler, Michael; Waag, Andreas; Shen, Hao; Prades, J Daniel

2014-12-17

Selectivity and low power consumption are major challenges in the development of sophisticated gas sensor devices. A sensor system is presented that unifies selective sensor-gas interactions and energy-harvesting properties, using defined organic-inorganic hybrid materials. Simulations of chemical-binding interactions and the consequent electronic surface modulation give more insight into the complex sensing mechanism of selective gas detection. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

CARbodies: Human Antibodies Against Cell Surface Tumor Antigens Selected From Repertoires Displayed on T Cell Chimeric Antigen Receptors

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Vanesa Alonso-Camino

2013-01-01

Full Text Available A human single-chain variable fragment (scFv antibody library was expressed on the surface of human T cells after transduction with lentiviral vectors (LVs. The repertoire was fused to a first-generation T cell receptor ζ (TCRζ-based chimeric antigen receptor (CAR. We used this library to isolate antibodies termed CARbodies that recognize antigens expressed on the tumor cell surface in a proof-of-principle system. After three rounds of activation-selection there was a clear repertoire restriction, with the emergence dominant clones. The CARbodies were purified from bacterial cultures as soluble and active proteins. Furthermore, to validate its potential application for adoptive cell therapy, human T cells were transduced with a LV encoding a second-generation costimulatory CAR (CARv2 bearing the selected CARbodies. Transduced human primary T cells expressed significant levels of the CARbodies-based CARv2 fusion protein on the cell surface, and importantly could be specifically activated, after stimulation with tumor cells. This approach is a promising tool for the generation of antibodies fully adapted to the display format (CAR and the selection context (cell synapse, which could extend the scope of current adoptive cell therapy strategies with CAR-redirected T cells.

Application of positron annihilation induced auger electron spectroscopy to the study of surface chemistry

International Nuclear Information System (INIS)

Weiss, A.H.; Yang, G.; Nangia, A.; Kim, J.H.; Fazleev, N.G.

1996-01-01

Positron annihilation induced Auger Electron Spectroscopy (PAES), makes use a beam of low energy positrons to excite Auger transitions by annihilating core electrons. This novel mechanism provides PAES with a number of unique features which distinguishes it from other methods of surface analysis. In PAES the very large collisionally induced secondary electron background which is present under the low energy Auger peaks using conventional techniques can be eliminated by using a positron beam whose energy is below the range of Auger electron energies. In addition, PAES is more surface selective than conventional Auger Spectroscopy because the PAES signal originates almost exclusively from the topmost atomic layer due to the fact that the positrons annihilating with the core electrons are trapped in an image correlation well just outside the surface. In this paper, recent applications of Positron Annihilation Induced Auger Electron Spectroscopy (PAES) to the study of surface structure and surface chemistry will be discussed including studies of the growth, alloying and inter-diffusion of ultrathin layers of metals, metals on semiconductors, and semiconductors on semiconductors. In addition, the possibilities for future application of PAES to the study of catalysis and surface chemistry will be outlined. (author)

Field Study of Infiltration Capacity Reduction of Porous Mixture Surfaces

Directory of Open Access Journals (Sweden)

Luis A. Sañudo-Fontaneda

2014-03-01

Full Text Available Porous surfaces have been used all over the world in source control techniques to minimize flooding problems in car parks. Several studies highlighted the reduction in the infiltration capacity of porous mixture surfaces after several years of use. Therefore, it is necessary to design and develop a new methodology to quantify this reduction and to identify the hypothetical differences in permeability between zones within the same car park bay due to the influence of static loads in the parked vehicles. With this aim, nine different zones were selected in order to check this hypothesis (four points under the wheels of a standard vehicle and five points between wheels. This article presents the infiltration capacity reduction results, using the LCS permeameter, of Polymer-Modified Porous Concrete (9 bays and Porous Asphalt (9 bays surfaces in the University of Cantabria Campus parking area (Spain 5 years after their construction. Statistical analysis methodology was proposed for assessing the results. Significant differences were observed in permeability and reduction in infiltration capacity in the case of porous concrete surfaces, while no differences were found for porous asphalt depending on the measurement zone.

Experimental and modelling studies on the exposure of wall surfaces to tritium gas in ambient room conditions

International Nuclear Information System (INIS)

Housiadas, C.; Douglas, K.

1995-01-01

An experimental set-up is used to carry out static exposure tests to study the uptake and oxidation of tritium released in ambient room air, routinely or accidentally, in the presence of selected surface materials. Tritium, in its elemental form at concentrations of the order of approx.0.4 GBq/m 3 (10 -2 Ci/m 3 ), is injected into the glass exposure chamber containing the selected surface material and air at atmospheric pressure. Periodically, samples of the chamber atmosphere are analysed, using liquid scintillation counting, to obtain the concentrations of HTO and T 2 . The exposures have been performed using aluminium, 316L stainless steel and painted stainless steel plates, as the selected surface materials. Results are compared with predictions using the ITER approved TMAP4 code. The results indicate practically the same conversion rate, of about 0.02% per day, for both the aluminium and stainless steel samples and give reasonable agreement with modelling predictions. Strong absorption of both T 2 and HTO by the painted surface is observed, suggesting the use of high values for the solubility constant to correctly predict this behaviour. 19 refs., 5 figs., 1 tab

Surface Characteristics and Biofilm Development on Selected Dental Ceramic Materials

Directory of Open Access Journals (Sweden)

Kyoung H. Kim

2017-01-01

Full Text Available Background. Intraoral adjustment and polishing of dental ceramics often affect their surface characteristics, promoting increased roughness and consequent biofilm growth. This study correlated surface roughness to biofilm development with four commercially available ceramic materials. Methods. Four ceramic materials (Vita Enamic®, Lava™ Ultimate, Vitablocs Mark II, and Wieland Reflex® were prepared as per manufacturer instructions. Seventeen specimens of each material were adjusted and polished to simulate clinical intraoral procedures and another seventeen remained unaltered. Specimens were analysed by SEM imaging, confocal microscopy, and crystal violet assay. Results. SEM images showed more irregular surface topography in adjusted specimens than their respective controls. Surface roughness (Ra values were greater in all materials following adjustments. All adjusted materials with the exception of Vitablocs Mark II promoted significantly greater biofilm growth relative to controls. Conclusion. Simulated intraoral polishing methods resulted in greater surface roughness and increased biofilm accumulation.

Materials selection of surface coatings in an advanced size reduction facility

International Nuclear Information System (INIS)

Briggs, J.L.; Younger, A.F.

1980-01-01

A materials selection test program was conducted to characterize optimum interior surface coatings for an advanced size reduction facility. The equipment to be processed by this facility consists of stainless steel apparatus (e.g., glove boxes, piping, and tanks) used for the chemical recovery of plutonium. Test results showed that a primary requirement for a satisfactory coating is ease of decontamination. A closely related concern is the resistance of paint films to nitric acid - plutonium environments. A vinyl copolymer base paint was the only coating, of eight paints tested, with properties that permitted satisfactory decontamination of plutonium and also performed equal to or better than the other paints in the chemical resistance, radiation stability, and impact tests

A high surface area Zr(IV)-based metal–organic framework showing stepwise gas adsorption and selective dye uptake

Energy Technology Data Exchange (ETDEWEB)

Lv, Xiu-Liang [Beijing Key Laboratory for Green Catalysis and Separation, Department of Chemistry and Chemical Engineering, Beijing University of Technology, Beijing 100124 (China); Tong, Minman; Huang, Hongliang [College of Chemical Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Wang, Bin; Gan, Lei [Beijing Key Laboratory for Green Catalysis and Separation, Department of Chemistry and Chemical Engineering, Beijing University of Technology, Beijing 100124 (China); Yang, Qingyuan [College of Chemical Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Zhong, Chongli [College of Chemical Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); State Key Laboratory of Organic–Inorganic Composites, Beijing University of Chemical Technology, Beijing 100029 (China); Li, Jian-Rong, E-mail: jrli@bjut.edu.cn [Beijing Key Laboratory for Green Catalysis and Separation, Department of Chemistry and Chemical Engineering, Beijing University of Technology, Beijing 100124 (China); State Key Laboratory of Organic–Inorganic Composites, Beijing University of Chemical Technology, Beijing 100029 (China)

2015-03-15

Exploitation of new metal–organic framework (MOF) materials with high surface areas has been attracting great attention in related research communities due to their broad potential applications. In this work, a new Zr(IV)-based MOF, [Zr{sub 6}O{sub 4}(OH){sub 4}(eddb){sub 6}] (BUT-30, H{sub 2}eddb=4,4′-(ethyne-1,2-diyl)dibenzoic acid) has been solvothermally synthesized, characterized, and explored for gases and dyes adsorptions. Single-crystal X-ray diffraction analysis demonstrates a three-dimensional cubic framework structure of this MOF, in which each Zr{sub 6}O{sub 4}(OH){sub 4} building unit is linked by 12 linear eddb ligands. BUT-30 has been found stable up to 400 °C and has a Brunauer–Emmett–Teller (BET) surface area as high as 3940.6 m{sup 2} g{sup −1} (based on the N{sub 2} adsorption at 77 K) and total pore volume of 1.55 cm{sup 3} g{sup −1}. It is more interesting that this MOF exhibits stepwise adsorption behaviors for Ar, N{sub 2}, and CO{sub 2} at low temperatures, and selective uptakes towards different ionic dyes. - Graphical abstract: A new Zr(IV)-based MOF with high surface area has been synthesized and structurally characterized, which shows stepwise gas adsorption at low temperature and selective dye uptake from solution. - Highlights: • A new Zr-based MOF was synthesized and structurally characterized. • This MOF shows a higher surface area compared with its analogous UiO-67 and 68. • This MOF shows a rare stepwise adsorption towards light gases at low temperature. • This MOF performs selective uptakes towards cationic dyes over anionic ones. • Using triple-bond spacer is confirmed feasible in enhancing MOF surface areas.

Modelling of nuclide migration for support of the site selection for near surface repository in Lithuania

International Nuclear Information System (INIS)

Kilda, R.; Poskas, P.; Ragaisis, V.

2006-01-01

Construction of the near surface repository (NSR) for disposal of short-lived low-and intermediate-level waste (LILW) is planned in Lithuania. Reference design of the repository was prepared. Site selection process is going on. Environmental Impact Assessment (EIA) Program and Report were prepared and are under review by regulators. Releases of radionuclides to water pathway and potential human exposure after closure of the NSR have been assessed for support of the site selection for NSR installation. Two candidate sites were taken under consideration. The assessments have been performed following ISAM methodology recommended by IAEA for safety assessments of near surface disposal facilities. The conceptual design of NSR as well as peculiarities of geological and hydro-geological environment relevant to each candidate site is taken into account. The results of the analysis as part of EIA Report are presented in the paper. It is demonstrated that estimated impact of potential radionuclide migration for both candidate sites is below dose constrain established by regulations of Lithuania. (author)

Selective Laser Sintering of PA2200: Effects of print parameters on density, accuracy, and surface roughness

Energy Technology Data Exchange (ETDEWEB)

Bajric, Sendin [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2017-06-12

Additive manufacturing needs a broader selection of materials for part production. In order for the Los Alamos National Laboratory (LANL) to investigate new materials for selective laser sintering (SLS), this paper reviews research on the effect of print parameters on part density, accuracy, and surface roughness of polyamide 12 (PA12, PA2200). The literature review serves to enhance the understanding of how changing the laser powder, scan speed, etc. will affect the mechanical properties of a commercial powder. By doing so, this understanding will help the investigation of new materials for SLS.

Black germanium selective absorber surfaces. Final technical report, September 1, 1978-June 30, 1979

Energy Technology Data Exchange (ETDEWEB)

Messier, R.; Vedam, K.; Krishnaswamy, S.V.

1979-12-01

Semiconductor films with an appropriate band gap (approx. 0.5 to 1.25 ev) have a high absorption coefficient in the solar spectrum region and high transmission in the IR thermal-emission region and thus make nearly ideal selective absorbers. However, due to their high refractive index, semiconductor films have high reflectance above their absorption edge which limits their total absorption. A coating which would retain the advantages of the semiconductor's selectivity and also reduce the reflectance from the present values of 30 to 50% to a level of less than 2% would be a significant advancement in the state of the art. This study describes work on the preparation and characterization of structurally anisotropic black Ge films by rf-sputtering and postdeposition etching. It has been shown that by controlling the sputtering preparation conditions of noncrystalline Ge films the surface microstructure can be drastically altered by simply etching in 30% H/sub 2/O/sub 2/. The total reflectance of the resulting surface was reduced from about 45% to less than 1%. Furthermore, the films appear black over a wide range of angles of incidence ( up to 45% from the normal). This flat black appearance is shown to be due to a dense array of aligned, needle-like protrusions which have an extremely high aspect ratio and both a cross-sectional area and a separation between the needles on th order of the wavelength of solar radiation. Black Ge films were obtained with a solar absorptance, ..cap alpha../sub S/, of greater than 0.99 in the best cases. Variation of ..cap alpha../sub S/ and epsilon/sub IR/ (IR emittance) with the thickness of the film and other preparation conditions is described. Further, the various microstructures are classified and understood on the basis of a structure zone model.

Selective adsorption of a supramolecular structure on flat and stepped gold surfaces

Science.gov (United States)

Peköz, Rengin; Donadio, Davide

2018-04-01

Halogenated aromatic molecules assemble on surfaces forming both hydrogen and halogen bonds. Even though these systems have been intensively studied on flat metal surfaces, high-index vicinal surfaces remain challenging, as they may induce complex adsorbate structures. The adsorption of 2,6-dibromoanthraquinone (2,6-DBAQ) on flat and stepped gold surfaces is studied by means of van der Waals corrected density functional theory. Equilibrium geometries and corresponding adsorption energies are systematically investigated for various different adsorption configurations. It is shown that bridge sites and step edges are the preferred adsorption sites for single molecules on flat and stepped surfaces, respectively. The role of van der Waals interactions, halogen bonds and hydrogen bonds are explored for a monolayer coverage of 2,6-DBAQ molecules, revealing that molecular flexibility and intermolecular interactions stabilize two-dimensional networks on both flat and stepped surfaces. Our results provide a rationale for experimental observation of molecular carpeting on high-index vicinal surfaces of transition metals.

Selection of replacement material for the failed surface level gauge wire in Hanford waste tanks

International Nuclear Information System (INIS)

Anantatmula, R.P.; Pitman, S.G.; Lund, A.L.

1995-10-01

Surface level gauges fabricated from AISI Type 316 stainless steel (316) wire failed after only a few weeks of operation in underground storage tanks at the Hanford Site. The wire failure was determined to be due to chloride ion assisted corrosion of the 316 wire. Radiation-induced breakdown of the polyvinyl chloride (PVC) riser liners is suspected to be the primary source of the chloride ions. An extensive literature search followed by expert concurrence was undertaken to select a replacement material for the wire. Platinum (Pt)-20 % Iridium (Ir) alloy was selected as the replacement material from tile candidate materials, P-20% Ir, Pt-1O% Rhodium (Rh), Pt-20%Rh and Hastelloy C-22. The selection was made on the basis of the alloy's immunity towards acidic and basic environments as well as its adequate tensile properties in the fully annealed state

Influence of Ultrasonic Surface Rolling on Microstructure and Wear Behavior of Selective Laser Melted Ti-6Al-4V Alloy

Directory of Open Access Journals (Sweden)

Zhen Wang

2017-10-01

Full Text Available The present article studied the effect of ultrasonic surface rolling process (USRP on the microstructure and wear behavior of a selective laser melted Ti-6Al-4V alloy. Surface characteristics were investigated using optical microscope, nano-indentation, scanning electron microscope, transmission electron microscope and laser scanning confocal microscope. Results indicated that the thickness of pore-free surfaces increased to 100~200 μm with the increasing ultrasonic surface rolling numbers. Severe work hardening occurred in the densified layer, resulting in the formation of refined grains, dislocation walls and deformation twins. After 1000 N 6 passes, about 15.5% and 14.1% increment in surficial Nano-hardness and Vickers-hardness was obtained, respectively. The hardness decreased gradually from the top surface to the substrate. Wear tests revealed that the friction coefficient declined from 0.74 (polished surface to 0.64 (USRP treated surface and the wear volume reduced from 0.205 mm−3 to 0.195 mm−3. The difference in wear volume between USRP treated and polished samples increased with sliding time. The enhanced wear resistance was concluded to be associated with the improvement of hardness and shear resistance and also the inhibition of delamination initiation.

Influence of Selective Laser Melting Processing Parameters of Co-Cr-W Powders on the Roughness of Exterior Surfaces

Science.gov (United States)

Baciu, M. A.; Baciu, E. R.; Bejinariu, C.; Toma, S. L.; Danila, A.; Baciu, C.

2018-06-01

Selective Laser Melting (SLM) represents an Additive Manufacturing method widely used in medical practice, mainly in dental medicine. The powder of 59% Co, 25% Cr, 2.5% W alloy (Starbond CoS Powder 55, S&S Scheftner C, Germany) was processed (SLM) on a Realizer SLM 50 device (SLM Solution, Germany). After laser processing and simple sanding with Al2O3 or two-phase sanding (Al2O3 and glass balls), measurements of surface roughness were conducted. This paper presents the influences exercised by laser power (P = 60 W, 80 W and 100 W), the scanning speed (vscan = 333 mm/s, 500 mm/s and 1000 mm/s) and exposure time (te = 20 µs, 40 µs and 60 µs) on the roughness of surfaces obtained by SLM processing. Based on the experimental results obtained for roughness (Ra), some recommendations regarding the choice of favorable combinations among the values of technological parameters under study in order to obtain the surface quality necessary for subsequent applications of the processed parts (SLM) have been made.

Surface-selective laser sintering of thermolabile polymer particles using water as heating sensitizer

Energy Technology Data Exchange (ETDEWEB)

Antonov, E N; Krotova, L I; Minaev, N V; Minaeva, S A; Mironov, A V; Popov, V K [Institute on Laser and Information Technologies of the Russian Academy of Sciencies, Troitsk, Moscow (Russian Federation); Bagratashvili, V N [Department of Chemistry, M.V. Lomonosov Moscow State University, Moscow (Russian Federation)

2015-11-30

We report the implementation of a novel scheme for surface-selective laser sintering (SSLS) of polymer particles, based on using water as a sensitizer of laser heating and sintering of particles as well as laser radiation at a wavelength of 1.94 μm, corresponding to the strong absorption band of water. A method of sintering powders of poly(lactide-co-glycolide), a hydrophobic bioresorbable polymer, after modifying its surface with an aqueous solution of hyaluronic acid is developed. The sintering thresholds for wetted polymer are by 3 – 4 times lower than those for sintering in air. The presence of water restricts the temperature of the heated polymer, preventing its thermal destruction. Polymer matrices with a developed porous structure are obtained. The proposed SSLS method can be applied to produce bioresorbable polymer matrices for tissue engineering. (interaction of laser radiation with matter. laser plasma)

Selectivity control of photosensitive structures based on gallium arsenide phosphide solid solutions by changing the rate of surface recombination

International Nuclear Information System (INIS)

Tarasov, S A; Andreev, M Y; Lamkin, I A; Solomonov, A V

2016-01-01

In this paper, we demonstrate the effect of surface recombination on spectral sensitivity of structures based on gallium arsenide phosphide solid solutions. Simulation of the effect for structures based on a p-n junction and a Schottky barrier was carried out. Photodetectors with different rates of surface recombination were fabricated by using different methods of preliminary treatment of the semiconductor surface. We experimentally demonstrated the possibility to control photodetector selectivity by altering the rate of surface recombination. The full width at half maximum was reduced by almost 4 times, while a relatively small decrease in sensitivity at the maximum was observed. (paper)

Selective Area Modification of Silicon Surface Wettability by Pulsed UV Laser Irradiation in Liquid Environment.

Science.gov (United States)

Liu, Neng; Moumanis, Khalid; Dubowski, Jan J

2015-11-09

The wettability of silicon (Si) is one of the important parameters in the technology of surface functionalization of this material and fabrication of biosensing devices. We report on a protocol of using KrF and ArF lasers irradiating Si (001) samples immersed in a liquid environment with low number of pulses and operating at moderately low pulse fluences to induce Si wettability modification. Wafers immersed for up to 4 hr in a 0.01% H2O2/H2O solution did not show measurable change in their initial contact angle (CA) ~75°. However, the 500-pulse KrF and ArF lasers irradiation of such wafers in a microchamber filled with 0.01% H2O2/H2O solution at 250 and 65 mJ/cm(2), respectively, has decreased the CA to near 15°, indicating the formation of a superhydrophilic surface. The formation of OH-terminated Si (001), with no measurable change of the wafer's surface morphology, has been confirmed by X-ray photoelectron spectroscopy and atomic force microscopy measurements. The selective area irradiated samples were then immersed in a biotin-conjugated fluorescein-stained nanospheres solution for 2 hr, resulting in a successful immobilization of the nanospheres in the non-irradiated area. This illustrates the potential of the method for selective area biofunctionalization and fabrication of advanced Si-based biosensing architectures. We also describe a similar protocol of irradiation of wafers immersed in methanol (CH3OH) using ArF laser operating at pulse fluence of 65 mJ/cm(2) and in situ formation of a strongly hydrophobic surface of Si (001) with the CA of 103°. The XPS results indicate ArF laser induced formation of Si-(OCH3)x compounds responsible for the observed hydrophobicity. However, no such compounds were found by XPS on the Si surface irradiated by KrF laser in methanol, demonstrating the inability of the KrF laser to photodissociate methanol and create -OCH3 radicals.

Surface modification of imprinted polymer microspheres with ultrathin hydrophilic shells to improve selective recognition of glutathione in aqueous media

Energy Technology Data Exchange (ETDEWEB)

Song, Renyuan, E-mail: songrenyuan0726@163.com; Hu, Xiaoling; Guan, Ping; Li, Ji; Du, Chunbao; Qian, Liwei; Wang, Chaoli

2016-03-01

A universal, effective approach addressing the classical limitations of hydrophobic molecularly imprinted polymer (MIP) microspheres was described. Two water-compatible MIP microspheres with ultrathin hydrophilic shells were synthesized by controllable surface-graft polymerization using a charged monomer (methacrylic acid) and uncharged monomer (N-isopropylacrylamide) as the hydrophilic functional monomers for the recognition of glutathione in the aqueous medium. The morphological and chemical characteristics of the as-prepared water-compatible MIP microspheres were investigated by scanning electron microscopy, Fourier transform infrared spectroscopy and contact angle measurements. Their selective recognition properties were investigated by static binding tests and compared with those of the ungrafted MIP microspheres. The results of this study showed that the both as-prepared water-compatible MIP microspheres effectively decreased non-specific binding and enhanced the imprinting factor significantly, and the water-compatible MIP microspheres prepared using N-isopropylacrylamide as monomer exhibited a more remarkable recognition property. In addition, the thickness of surface-grafted hydrophilic layer was well controlled by adjusting the irradiation time to obtain the excellent recognition property. Finally, the applicability of the as-prepared water-compatible MIP microspheres as solid-phase extraction materials was investigated by competitive binding tests using a mixture of glutathione and its analogs. - Highlights: • Ultrathin hydrophilic shell was synthesized by controllable SIP approach. • Low nonspecific binding, high imprinting factor and selectivity were achieved. • Value of imprinting factor was controlled by adjusting irradiation time. • Selective solid-phase extraction of glutathione from a mixed solution of peptides.

Analytical Solution for Elliptical Cloaks Based on The Frequency Selective Surface

Directory of Open Access Journals (Sweden)

E. Ghasemi Mizuji

2015-01-01

Full Text Available In this paper the elliptical dielectric cylinder which is covered with FSS cloak is considered. Frequency selective surface cloak which Alu named it mantle cloak is one of the recent techniques for cloaking. In this method an appropriate FSS can act as cloaking device for suppressing  the scattering of object  in the desired frequency. With using this method the dimension of the cloaks is extremely reduced. By this proposed structure, the RCS of elliptical cylinder  is reduced about 10-20 dB and designed cloak has an appropriate performance.  The analytical solution for the wave in each layer is presented and with using simulation, the electric field and the scattering pattern has been drawn.

Fracture behaviour of a magnesium–aluminium alloy treated by selective laser surface melting treatment

International Nuclear Information System (INIS)

Taltavull, C.; López, A.J.; Torres, B.; Rams, J.

2014-01-01

Highlights: • β-Mg 17 Al 12 presents fragile fracture behavior decreasing the ductility of AZ91D. • SLSM treatment only modifies the β-Mg 17 Al 12 phase whilst α-Mg remains unaltered. • In-situ SEM bending test allows to observe and data record of the crack propagation. • Eutectic microestructure of modified β-phase presents ductile fracture behaviour. • Fracture toughness of laser treated specimen is 40% greater than as-received alloy. - Abstract: Fracture behaviour of AZ91D magnesium alloy is dominated by the brittle fracture of the β-Mg 17 Al 12 phase so its modification is required to improve the toughness of this alloy. The novel laser treatment named as Selective Laser Surface Melting (SLSM) is characterized by the microstructural modification of the β-Mg 17 Al 12 phase without altering the α-Mg matrix. We have studied the effect of the selected microstructural modification induced by the laser treatment in the fracture behaviour of the alloy has been studied using in situ Scanning Electron Microscopy bending test. This test configuration allows the in situ observation of the crack progression and the record of the load–displacement curve. It has been observed that the microstructural modification introduced by SLSM causes an increase of 40% of the fracture toughness of the treated specimen. This phenomenon can be related with the transition from brittle to ductile fracture behaviour of the laser modified β-phase

Clinical Study Monitoring the pH on Tooth Surfaces in Patients with and without Erosion

OpenAIRE

Lussi, Adrian; von Salis-Marincek, Maya; Ganss, Carolina; Hellwig, Elmar; Cheaib, Zeinab; Jaeggi, Thomas

2012-01-01

The aim of this study was to compare tooth surface pH after drinking orange juice or water in 39 patients with dental erosion and in 17 controls. The following investigations were carried out: measurement of pH values on selected tooth surfaces after ingestion of orange juice followed by ingestion of water (acid clearance), measurement of salivary flow rate and buffering capacity. Compared with the controls, patients with erosion showed significantly greater decreases in pH after drinking ora...

Molecular dynamics study of Pb-substituted Cu(1 0 0) surface layers

Energy Technology Data Exchange (ETDEWEB)

Evangelakis, G.A. [Department of Physics, University of Ioannina, PO Box 1186, Ioannina 45110 (Greece); Pontikis, V., E-mail: Vassilis.pontikis@cea.f [Laboratoire des Solides Irradies, CEA-DRECAM, 91191 Gif-sur-Yvette Cedex (France)

2009-08-26

Using molecular dynamics (MD) and phenomenological n-body potentials from the literature, we have studied the structure of the uppermost layers of low-index surfaces in copper after partial substitution of copper by lead atoms at randomly selected sites. We found that lead atoms substituting copper strongly perturb the positions of nearest and of next-nearest neighbors thus triggering the setup of a disordered, nanometer-thick amorphous-like surface layer. Equilibrium atomic density profiles, computed along the [1 0 0] crystallographic direction, show that amorphous overlayers are largely metastable whereas the system displays a structured compositional profile of lead segregating at the interfaces. Similarities between our results and experimental findings are briefly discussed.

Molecular dynamics study of Pb-substituted Cu(1 0 0) surface layers

International Nuclear Information System (INIS)

Evangelakis, G.A.; Pontikis, V.

2009-01-01

Using molecular dynamics (MD) and phenomenological n-body potentials from the literature, we have studied the structure of the uppermost layers of low-index surfaces in copper after partial substitution of copper by lead atoms at randomly selected sites. We found that lead atoms substituting copper strongly perturb the positions of nearest and of next-nearest neighbors thus triggering the setup of a disordered, nanometer-thick amorphous-like surface layer. Equilibrium atomic density profiles, computed along the [1 0 0] crystallographic direction, show that amorphous overlayers are largely metastable whereas the system displays a structured compositional profile of lead segregating at the interfaces. Similarities between our results and experimental findings are briefly discussed.

All-dielectric metamaterial frequency selective surface based on spatial arrangement ceramic resonators

Science.gov (United States)

Li, Liyang; Wang, Jun; Feng, Mingde; Ma, Hua; Wang, Jiafu; Du, Hongliang; Qu, Shaobo

In this paper, we demonstrate a method of designing all-dielectric metamaterial frequency selective surface (FSS) with ceramic resonators in spatial arrangement. Compared with the traditional way, spatial arrangement provides a flexible way to handle the permutation and combination of different ceramic resonators. With this method, the resonance response can be adjusted easily to achieve pass/stop band effects. As an example, a stop band spatial arrangement all-dielectric metamaterial FSS is designed. Its working band is in 11.65-12.23GHz. By adjusting permittivity and geometrical parameters of ceramic resonators, we can easily modulate the resonances, band pass or band stop characteristic, as well as the working band.

Cermet based solar selective absorbers : further selectivity improvement and developing new fabrication technique

OpenAIRE

Nejati, Mohammadreza

2008-01-01

Spectral selectivity of cermet based selective absorbers were increased by inducing surface roughness on the surface of the cermet layer using a roughening technique (deposition on hot substrates) or by micro-structuring the metallic substrates before deposition of the absorber coating using laser and imprint structuring techniques. Cu-Al2O3 cermet absorbers with very rough surfaces and excellent selectivity were obtained by employing a roughness template layer under the infrared reflective l...

Uniform deposition of size-selected clusters using Lissajous scanning

International Nuclear Information System (INIS)

Beniya, Atsushi; Watanabe, Yoshihide; Hirata, Hirohito

2016-01-01

Size-selected clusters can be deposited on the surface using size-selected cluster ion beams. However, because of the cross-sectional intensity distribution of the ion beam, it is difficult to define the coverage of the deposited clusters. The aggregation probability of the cluster depends on coverage, whereas cluster size on the surface depends on the position, despite the size-selected clusters are deposited. It is crucial, therefore, to deposit clusters uniformly on the surface. In this study, size-selected clusters were deposited uniformly on surfaces by scanning the cluster ions in the form of Lissajous pattern. Two sets of deflector electrodes set in orthogonal directions were placed in front of the sample surface. Triangular waves were applied to the electrodes with an irrational frequency ratio to ensure that the ion trajectory filled the sample surface. The advantages of this method are simplicity and low cost of setup compared with raster scanning method. The authors further investigated CO adsorption on size-selected Pt n (n = 7, 15, 20) clusters uniformly deposited on the Al 2 O 3 /NiAl(110) surface and demonstrated the importance of uniform deposition.

Uniform deposition of size-selected clusters using Lissajous scanning

Energy Technology Data Exchange (ETDEWEB)

Beniya, Atsushi; Watanabe, Yoshihide, E-mail: e0827@mosk.tytlabs.co.jp [Toyota Central R& D Labs., Inc., 41-1 Yokomichi, Nagakute, Aichi 480-1192 (Japan); Hirata, Hirohito [Toyota Motor Corporation, 1200 Mishuku, Susono, Shizuoka 410-1193 (Japan)

2016-05-15

Size-selected clusters can be deposited on the surface using size-selected cluster ion beams. However, because of the cross-sectional intensity distribution of the ion beam, it is difficult to define the coverage of the deposited clusters. The aggregation probability of the cluster depends on coverage, whereas cluster size on the surface depends on the position, despite the size-selected clusters are deposited. It is crucial, therefore, to deposit clusters uniformly on the surface. In this study, size-selected clusters were deposited uniformly on surfaces by scanning the cluster ions in the form of Lissajous pattern. Two sets of deflector electrodes set in orthogonal directions were placed in front of the sample surface. Triangular waves were applied to the electrodes with an irrational frequency ratio to ensure that the ion trajectory filled the sample surface. The advantages of this method are simplicity and low cost of setup compared with raster scanning method. The authors further investigated CO adsorption on size-selected Pt{sub n} (n = 7, 15, 20) clusters uniformly deposited on the Al{sub 2}O{sub 3}/NiAl(110) surface and demonstrated the importance of uniform deposition.

An investigation on the performance characteristics of solar flat plate collector with different selective surface coatings

Energy Technology Data Exchange (ETDEWEB)

Madhukeshwara, N. [Department of Mechanical Engineering, B.I.E.T, Davanagere, Karnataka (India); Prakash, E.S. [Department of Studies in Mechanical Engineering, U.B.D.T.C.E, Davanagere, Karnataka (India)

2012-07-01

In the present work, investigations are made to study performance characteristics of solar flat plate collector with different selective surface coatings. Flat plate collector is one of the important solar energy trapping device which uses air or water as working fluid. Of the many solar collector concepts presently being developed, the relative simple flat plate solar collector has found the widest application so far. Its characteristics are known, and compared with other collector types, it is the easiest and least expensive to fabricate, install, and maintain. Moreover, it is capable of using both the diffuse and the direct beam solar radiation. For residential and commercial use, flat plate collectors can produce heat at sufficiently high temperatures to heat swimming pools, domestic hot water, and buildings; they also can operate a cooling unit, particularly if the incident sunlight is increased by the use of reflector. Temperatures up to 70 C are easily attained by flat plate collectors. With very careful engineering using special surfaces, reflectors to increase the incident radiation and heat resistant materials, higher operating temperatures are feasible.

Surface and impurity studies in ORMAK and ISX

Energy Technology Data Exchange (ETDEWEB)

Colchin, R.J.; Clausing, R.E.; Emerson, L.C.; Heatherly, L.; Isler, R.C.

1977-02-01

The ORMAK vacuum liner is constructed of stainless steel overcoated with a thin platinum diffusion barrier and a final layer of gold. Gold was selected as the vacuum surface because it is chemically inert to the adsorption of common gases. However, gold surfaces do adsorb hydrocarbons, and carbon (along with oxygen) was the principal plasma contaminant during the first two years of ORMAK operation. Upon switching discharge-cleaning gases from hydrogen to oxygen, carbon levels dropped until carbon is no longer a significant contaminant; residual hydrocarbons can now be controlled either by hydrogen or by oxygen discharge cleaning. The principal measured plasma contaminant in ORMAK is now oxygen. Samples taken from the ORMAK liner and analyzed by Auger electron spectroscopy reveal the presence of iron and oxygen. There is evidence from a SXAPS (Soft X-ray Appearance Potential Spectroscopy) probe of iron and chromium diffusion from the stainless steel through the gold surface in spite of the platinum diffusion barrier. The iron and chromium provide surface oxidation sites, and SXAPS analysis shows that these metals exist as oxides.

Chlorhexidine controlled-release profile after EDTA root surface etching: an in vivo study.

Science.gov (United States)

Gamal, Ahmed Y; Kumper, Radi M; Sadek, Hesham S; El Destawy, Mahmoud T

2011-05-01

The main objective of the present study was to quantify chlorhexidine (CHX) release after the use of CHX-EDTA root surface treatment as a local-delivery antimicrobial vehicle. Twenty non-smoking patients clinically diagnosed as having moderate-to-severe chronic periodontitis were selected to participate in this study. After cause-related therapy, one site in every patient received defect overfill with CHX gel 2% (20 sites). In addition, twenty contralateral sites received defect fill of CHX gel after 3 minutes of 24% EDTA gel root surface etching (20 sites). Gingival crevicular fluid samples were collected at 1, 3, 7, and 14 days post-therapy. The CHX-EDTA group showed statistically significantly higher levels of CHX than those of the control group at 1, 3, and 7 days. At 14 days, the CHX-EDTA group showed 0.8 mg/mL values. The use of CHX-EDTA root surface treatment as a local-delivery antimicrobial improves CHX substantivity.

ITER site selection studies in Spain

International Nuclear Information System (INIS)

Medrano, M.; Alejaldre, C.; Doncel, J.; Garcia, A.; Ibarra, A.; Jimenez, J.A.; Sanchez de Mora, M.A.; Alcala, F.; Diez, J.E.; Dominguez, M.; Albisu, F.

2003-01-01

The studies carried out to evaluate and select a candidate site for International Thermonuclear Experimental Reactor (ITER) construction in Spain are presented in this paper. The ITER design, completed in July 2001, considered a number of technical requirements that must be fulfilled by the selected site. Several assumptions concerning the ITER site were made in order to carry on the design before final site selection. In the studies undertaken for ITER site selection in Spain, the referred technical requirements and assumptions were applied across the whole of Spain and two areas were identified as being preferential. These areas are on the Mediterranean coast and are situated in the Catalan and Valencian regions. A comparative evaluation based on technical characteristics for the concrete plots, proposed within the preferential areas, has been done. The result of these studies was the selection of a site that was deemed to be the most competitive--Vandellos (Tarragona)--and it was proposed to the European Commission for detailed studies in order to be considered as a possible European site for ITER construction. Another key factor for hosting ITER in Spain, is the licensing process. The present status is summarised in this paper

Selective binding of oligonucleotide on TiO{sub 2} surfaces modified by swift heavy ion beam lithography

Energy Technology Data Exchange (ETDEWEB)

Vicente Pérez-Girón, J. [Nanoate, S.L. C/Poeta Rafael Morales 2, San Sebastian de los Reyes, 28702 Madrid (Spain); Emerging Viruses Department Heinrich Pette Institute, Hamburg 20251 (Germany); Hirtz, M. [Institute of Nanotechnology (INT) and Karlsruhe Nano Micro Facility (KNMF), Karlsruhe Institute of Technology - KIT, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); McAtamney, C.; Bell, A.P. [Advanced Microscopy Laboratory, CRANN, Trinity College Dublin, Dublin 2 (Ireland); Antonio Mas, J. [Laboratorio de Genómica del Centro de Apoyo Tecnológico, Universidad Rey Juan Carlos, Campus de Alcorcón 28922, Madrid (Spain); Jaafar, M. [Nanoate, S.L. C/Poeta Rafael Morales 2, San Sebastian de los Reyes, 28702 Madrid (Spain); Departamento de Física de la Materia Condensada, Facultad de Ciencias, Universidad Autónoma de Madrid, Campus de Cantoblanco, 28049 Madrid (Spain); Luis, O. de [Nanoate, S.L. C/Poeta Rafael Morales 2, San Sebastian de los Reyes, 28702 Madrid (Spain); Departamento de Bioquímica, Fisiología y Genética Molecular, Facultad de Ciencias de la Salud, Universidad Rey Juan Carlos, Campus de Alcorcón, 28922 Madrid (Spain); Fuchs, H. [Institute of Nanotechnology (INT) and Karlsruhe Nano Micro Facility (KNMF), Karlsruhe Institute of Technology - KIT, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Physical Institute and Center for Nanotechnology (CeNTech), Wilhelm-Klemm-Straße 10, University of Münster (Germany); and others

2014-11-15

We have used swift heavy-ion beam based lithography to create patterned bio-functional surfaces on rutile TiO{sub 2} single crystals. The applied lithography method generates a permanent and well defined periodic structure of micrometre sized square holes having nanostructured TiO{sub 2} surfaces, presenting different physical and chemical properties compared to the surrounding rutile single crystal surface. On the patterned substrates selective binding of oligonucleotides molecules is possible at the surfaces of the holes. This immobilisation process is only being controlled by UV light exposure. The patterned transparent substrates are compatible with fluorescence detection techniques, are mechanically robust, have a high tolerance to extreme chemical and temperature environments, and apparently do not degrade after ten cycles of use. These qualities make the patterned TiO{sub 2} substrates useful for potential biosensor applications.

Kinetics studies following state-selective laser excitation

International Nuclear Information System (INIS)

Keto, J.W.

1994-04-01

The objective of this contract was the study of state-to-state, electronic energy transfer reactions relevant to the excited state chemistry observed in discharges. We studied deactivation reactions and excitation transfer in collisions of excited states of xenon and krypton atoms with Ar, Kr, Xe and chlorine. The reactant states were excited selectively in two-photon transitions using tunable u.v. and v.u.v. lasers. Excited states produced by the collision were observed by their fluorescence. Reaction rates were measured by observing the time dependent decay of signals from reactant and product channels. In addition we measured interaction potentials of the reactants by laser spectroscopy where the laser induced fluorescence or ionization is measured as a function of laser wavelength (excitation spectra) or by measuring fluorescence spectra at fixed laser frequencies with monochromators. The spectra were obtained in the form of either lineshapes or individual lines from rovibrational transitions of bound states. Our research then required several categories of experiments in order to fully understand a reaction process: 1. High resolution laser spectroscopy of bound molecules or lineshapes of colliding pairs is used to determine potential curves for reactants. 2. Direct measurements of state-to-state reaction rates were measured by studying the time dependent loss of excited reactants and the time dependent formation of products. 3. The energy selectivity of a laser can be used to excite reactants on an excited surface with controlled internuclear configurations. For free states of reactants (as exist in a gas cell) this has been termed laser assisted reactions, while for initially bound states (as chemically bound reactants or dimers formed in supersonic beams) the experiments have been termed photo-fragmentation spectroscopy

Studies on Gas Sensing Performance of Pure and Surface Chrominated Indium Oxide Thick Film Resistors

Directory of Open Access Journals (Sweden)

D. N. CHAVAN

2010-12-01

Full Text Available The thick films of AR grade In2O3 were prepared by standard screen-printing technique. The gas sensing performance of thick film was tested for various gases. It showed maximum gas response to ethanol vapor at 350 oC for 80 ppm. To improve the gas response and selectivity of the film towards a particular gas, In2O3 thick films were modified by dipping them in an aqueous solution of 0.1 M CrO3 for different intervals of time. The surface chrominated (20 min In2O3 thick film showed maximum response to H2S gas (40 ppm than pure In2O3 thick film at 250 oC. Chromium oxide on the surface of the film shifts the gas response from ethanol vapor to H2S gas. A systematic study of sensing performance of the sensor indicates the key role played by chromium oxide on the surface of thick film. The selectivity, gas response and recovery time of the sensor were measured and presented.

Selecting activated carbon for water and wastewater treatability studies

Energy Technology Data Exchange (ETDEWEB)

Zhang, W.; Chang, Q.G.; Liu, W.D.; Li, B.J.; Jiang, W.X.; Fu, L.J.; Ying, W.C. [East China University of Chemical Technology, Shanghai (China)

2007-10-15

A series of follow-up investigations were performed to produce data for improving the four-indicator carbon selection method that we developed to identify high-potential activated carbons effective for removing specific organic water pollutants. The carbon's pore structure and surface chemistry are dependent on the raw material and the activation process. Coconut carbons have relatively more small pores than large pores; coal and apricot nutshell/walnut shell fruit carbons have the desirable pore structures for removing adsorbates of all sizes. Chemical activation, excessive activation, and/or thermal reactivation enlarge small pores, resulting in reduced phenol number and higher tannic acid number. Activated carbon's phenol, iodine, methylene blue, and tannic acid numbers are convenient indicators of its surface area and pore volume of pore diameters < 10, 10-15, 15-28, and > 28 angstrom, respectively. The phenol number of a carbon is also a good indicator of its surface acidity of oxygen-containing organic functional groups that affect the adsorptive capacity for aromatic and other small polar organics. The tannic acid number is an indicator of carbon's capacity for large, high-molecular-weight natural organic precursors of disinfection by-products in water treatment. The experimental results for removing nitrobenzene, methyl-tert-butyl ether, 4,4-bisphenol, humic acid, and the organic constituents of a biologically treated coking-plant effluent have demonstrated the effectiveness of this capacity-indicator-based method of carbon selection.

Surface stress sensor based on MEMS Fabry-Perot interferometer with high wavelength selectivity for label-free biosensing

Science.gov (United States)

Takahashi, Toshiaki; Hizawa, Takeshi; Misawa, Nobuo; Taki, Miki; Sawada, Kazuaki; Takahashi, Kazuhiro

2018-05-01

We have developed a surface stress sensor based on a microelectromechanical Fabry-Perot interferometer with high wavelength selectivity by using Au half-mirrors, for highly sensitive label-free biosensing. When the target molecule is adsorbed by the antigen-antibody reaction onto a movable membrane with a thin Au film, which acts as an upper mirror of the optical interferometer, the amount of deflection of the movable membrane deflected by the change in surface stress can be detected with high sensitivity. To improve the signal at the small membrane deflection region of this biosensor resulting in detection of low concentration molecules, by integrating 50 nm-thick Au half-mirrors, the wavelength selectivity of the optical interferometer has been successfully improved 6.6 times. Furthermore, the peak shift in the reflection spectrum due to the adsorption of bovine serum albumin (BSA) antigen with a concentration of 10 ng ml-l by the antigen-antibody reaction was spectroscopically measured on the fabricated optical interferometer, and the deflection amount of the movable membrane after 10 min treatment was 2.4 times larger than that of nonspecific adsorption with the avidin molecules. This result indicated that the proposed sensor can be used for selective detection of low-concentration target antigen molecules.

Selective interaction of heparin with the variable region 3 within surface glycoprotein of laboratory-adapted feline immunodeficiency virus.

Directory of Open Access Journals (Sweden)

Qiong-Ying Hu

Full Text Available Heparan sulfate proteoglycans (HSPG can act as binding receptors for certain laboratory-adapted (TCA strains of feline immunodeficiency virus (FIV and human immunodeficiency virus (HIV. Heparin, a soluble heparin sulfate (HS, can inhibit TCA HIV and FIV entry mediated by HSPG interaction in vitro. In the present study, we further determined the selective interaction of heparin with the V3 loop of TCA of FIV. Our current results indicate that heparin selectively inhibits infection by TCA strains, but not for field isolates (FS. Heparin also specifically interferes with TCA surface glycoprotein (SU binding to CXCR4, by interactions with HSPG binding sites on the V3 loop of the FIV envelope protein. Peptides representing either the N- or C-terminal side of the V3 loop and containing HSPG binding sites were able to compete away the heparin block of TCA SU binding to CXCR4. Heparin does not interfere with the interaction of SU with anti-V3 antibodies that target the CXCR4 binding region or with the interaction between FS FIV and anti-V3 antibodies since FS SU has no HSPG binding sites within the HSPG binding region. Our data show that heparin blocks TCA FIV infection or entry not only through its competition of HSPG on the cell surface interaction with SU, but also by its interference with CXCR4 binding to SU. These studies aid in the design and development of heparin derivatives or analogues that can inhibit steps in virus infection and are informative regarding the HSPG/SU interaction.

Toward selective, sensitive, and discriminative detection of Hg(2+) and Cd(2+)via pH-modulated surface chemistry of glutathione-capped gold nanoclusters.

Science.gov (United States)

Huang, Pengcheng; Li, Sha; Gao, Nan; Wu, Fangying

2015-11-07

Heavy metal pollution can exert severe effects on the environment and human health. Simple, selective, and sensitive detection of heavy metal ions, especially two or more, using a single probe, is thereby of great importance. In this study, we report a new and facile strategy for discriminative detection of Hg(2+) and Cd(2+) with high selectivity and sensitivity via pH-modulated surface chemistry of the glutathione-capped gold NCs (GSH-Au NCs). By simply adjusting pH values of the colloidal solution of the NCs, Hg(2+) could specifically turn off the fluorescence under acidic pH, however, Cd(2+) could exclusively turn on the fluorescence under alkaline pH. This enables the NCs to serve as a dual fluorescent sensor for Hg(2+) and Cd(2+). We demonstrate that these two opposing sensing modes are presumably due to different interaction mechanisms: Hg(2+) induces aggregation by dissociating GSH from the Au surface via robust coordination and, Cd(2+) could passivate the Au surface by forming a Cd-GSH complex with a compact structure. Finally, the present strategy is successfully exploited to separately determine Hg(2+) and Cd(2+) in environmental water samples.

Studies on the surface modification of TiN coatings using MEVVA ion implantation with selected metallic species

International Nuclear Information System (INIS)

Ward, L.P.; Purushotham, K.P.; Manory, R.R.

2016-01-01

Highlights: • Reduced surface roughness was observed after ion implantation. • W implantation increased residual stress. • Reduced friction and wear accompanied Mo implantation. • Mo implanted layer was more resistant to breakdown during wear testing. • Ion implantation effects can be complex on various implanting species properties. - Abstract: Improvement in the performance of TiN coatings can be achieved using surface modification techniques such as ion implantation. In the present study, physical vapor deposited (PVD) TiN coatings were implanted with Cr, Zr, Nb, Mo and W using the metal evaporation vacuum arc (MEVVA) technique at a constant nominal dose of 4 × 10 16 ions cm −2 for all species. The samples were characterized before and after implantation, using Rutherford backscattering (RBS), glancing incident angle X-ray diffraction (GIXRD), atomic force microscopy (AFM) and optical microscopy. Friction and wear studies were performed under dry sliding conditions using a pin-on-disc CSEM Tribometer at 1 N load and 450 m sliding distance. A reduction in the grain size and surface roughness was observed after implantation with all five species. Little variation was observed in the residual stress values for all implanted TiN coatings, except for W implanted TiN which showed a pronounced increase in compressive residual stress. Mo-implanted samples showed a lower coefficient of friction and higher resistance to breakdown during the initial stages of testing than as-received samples. Significant reduction in wear rate was observed after implanting with Zr and Mo ions compared with unimplanted TiN. The presence of the Ti 2 N phase was observed with Cr implantation.

Polymer grafting surface as templates for the site-selective metallization

Energy Technology Data Exchange (ETDEWEB)

Yang, Fang [College of Pharmacy, Guangxi University of Chinese Medicine, Nanning 530001 (China); College of Chemistry and Life Science, Guangxi Teachers Education University, Nanning 530001 (China); Li, Peiyuan, E-mail: lipearpear@yahoo.cn [College of Pharmacy, Guangxi University of Chinese Medicine, Nanning 530001 (China); Li, Xiangcheng [School of computer, electronics and information, Guangxi University, Nanning 530001 (China); Huo, Lini [College of Pharmacy, Guangxi University of Chinese Medicine, Nanning 530001 (China); Chen, Jinhao [College of Chemistry and Life Science, Guangxi Teachers Education University, Nanning 530001 (China); Chen, Rui [College of Pharmacy, Guangxi University of Chinese Medicine, Nanning 530001 (China); Na, Wei; Tang, Wanning; Liang, Lifang [College of Chemistry and Life Science, Guangxi Teachers Education University, Nanning 530001 (China); Su, Wei, E-mail: aaasuwei@yahoo.com.cn [College of Chemistry and Life Science, Guangxi Teachers Education University, Nanning 530001 (China)

2013-06-01

We report a simple, low-cost and universal method for the fabrication of copper circuit patterns on a wide range of flexible polymeric substrates. This method relies on procedures to modify the polymeric substrates with grafted polymer template to form surface-bound N-containing groups, which can bind palladium catalysts that subsequently initiate the site-selective deposition of copper granular layer patterns. The fabrications of patterned copper films were demonstrated on three kinds of flexible polymeric films including poly(imide) (PI), poly(ethylene naphthalate) (PEN) and poly(ethylene terephthalate) (PET) with minimum feature sizes of 200 μm. The films were characterized by ATR FT-IR, contact angle, XPS, XRD, TEM, SEM. Furthermore, the copper layered structure shows good adhesion with polymeric film. This method, which provides a promising strategy for the fabrication of copper circuit patterns on flexible polymeric substrates, has the potential in manufacturing conductive features adopted in various fields including modern electronics, opto-electronics and photovoltaic applications.

Optically transparent frequency selective surfaces on flexible thin plastic substrates

Energy Technology Data Exchange (ETDEWEB)

Dewani, Aliya A., E-mail: a.ashraf@griffith.edu.au; O’Keefe, Steven G.; Thiel, David V.; Galehdar, Amir [School Of Electrical Engineering, Griffith University, Brisbane, 4111 (Australia)

2015-02-15

A novel 2D simple low cost frequency selective surface was screen printed on thin (0.21 mm), flexible transparent plastic substrate (relative permittivity 3.2). It was designed, fabricated and tested in the frequency range 10-20 GHz. The plane wave transmission and reflection coefficients agreed with numerical modelling. The effective permittivity and thickness of the backing sheet has a significant effect on the frequency characteristics. The stop band frequency reduced from 15GHz (no backing) to 12.5GHz with polycarbonate. The plastic substrate thickness beyond 1.8mm has minimal effect on the resonant frequency. While the inner element spacing controls the stop-band frequency, the substrate thickness controls the bandwidth. The screen printing technique provided a simple, low cost FSS fabrication method to produce flexible, conformal, optically transparent and bio-degradable FSS structures which can find their use in electromagnetic shielding and filtering applications in radomes, reflector antennas, beam splitters and polarizers.

Optically transparent frequency selective surfaces on flexible thin plastic substrates

Directory of Open Access Journals (Sweden)

Aliya A. Dewani

2015-02-01

Full Text Available A novel 2D simple low cost frequency selective surface was screen printed on thin (0.21 mm, flexible transparent plastic substrate (relative permittivity 3.2. It was designed, fabricated and tested in the frequency range 10-20 GHz. The plane wave transmission and reflection coefficients agreed with numerical modelling. The effective permittivity and thickness of the backing sheet has a significant effect on the frequency characteristics. The stop band frequency reduced from 15GHz (no backing to 12.5GHz with polycarbonate. The plastic substrate thickness beyond 1.8mm has minimal effect on the resonant frequency. While the inner element spacing controls the stop-band frequency, the substrate thickness controls the bandwidth. The screen printing technique provided a simple, low cost FSS fabrication method to produce flexible, conformal, optically transparent and bio-degradable FSS structures which can find their use in electromagnetic shielding and filtering applications in radomes, reflector antennas, beam splitters and polarizers.

Optically transparent frequency selective surfaces on flexible thin plastic substrates

Science.gov (United States)

Dewani, Aliya A.; O'Keefe, Steven G.; Thiel, David V.; Galehdar, Amir

2015-02-01

A novel 2D simple low cost frequency selective surface was screen printed on thin (0.21 mm), flexible transparent plastic substrate (relative permittivity 3.2). It was designed, fabricated and tested in the frequency range 10-20 GHz. The plane wave transmission and reflection coefficients agreed with numerical modelling. The effective permittivity and thickness of the backing sheet has a significant effect on the frequency characteristics. The stop band frequency reduced from 15GHz (no backing) to 12.5GHz with polycarbonate. The plastic substrate thickness beyond 1.8mm has minimal effect on the resonant frequency. While the inner element spacing controls the stop-band frequency, the substrate thickness controls the bandwidth. The screen printing technique provided a simple, low cost FSS fabrication method to produce flexible, conformal, optically transparent and bio-degradable FSS structures which can find their use in electromagnetic shielding and filtering applications in radomes, reflector antennas, beam splitters and polarizers.

Polymer grafting surface as templates for the site-selective metallization

International Nuclear Information System (INIS)

Yang, Fang; Li, Peiyuan; Li, Xiangcheng; Huo, Lini; Chen, Jinhao; Chen, Rui; Na, Wei; Tang, Wanning; Liang, Lifang; Su, Wei

2013-01-01

We report a simple, low-cost and universal method for the fabrication of copper circuit patterns on a wide range of flexible polymeric substrates. This method relies on procedures to modify the polymeric substrates with grafted polymer template to form surface-bound N-containing groups, which can bind palladium catalysts that subsequently initiate the site-selective deposition of copper granular layer patterns. The fabrications of patterned copper films were demonstrated on three kinds of flexible polymeric films including poly(imide) (PI), poly(ethylene naphthalate) (PEN) and poly(ethylene terephthalate) (PET) with minimum feature sizes of 200 μm. The films were characterized by ATR FT-IR, contact angle, XPS, XRD, TEM, SEM. Furthermore, the copper layered structure shows good adhesion with polymeric film. This method, which provides a promising strategy for the fabrication of copper circuit patterns on flexible polymeric substrates, has the potential in manufacturing conductive features adopted in various fields including modern electronics, opto-electronics and photovoltaic applications.

Study on electroactive and electrocatalytic surfaces of single walled carbon nanotube-modified electrodes

Energy Technology Data Exchange (ETDEWEB)

Salinas-Torres, David [Departamento de Quimica Fisica and Instituto Universitario de Materiales de Alicante, Universidad de Alicante, Apdo. de Correos 99, E-03080 Alicante (Spain); Huerta, Francisco [Departamento de Ingenieria Textil y Papelera, Universidad Politecnica de Valencia, Plaza Ferrandiz y Carbonell, 1. E-03801 Alcoy (Spain); Montilla, Francisco, E-mail: francisco.montilla@ua.e [Departamento de Quimica Fisica and Instituto Universitario de Materiales de Alicante, Universidad de Alicante, Apdo. de Correos 99, E-03080 Alicante (Spain); Morallon, Emilia [Departamento de Quimica Fisica and Instituto Universitario de Materiales de Alicante, Universidad de Alicante, Apdo. de Correos 99, E-03080 Alicante (Spain)

2011-02-01

An investigation of the electrocatalysis of single-walled carbon nanotubes modified electrodes has been performed in this work. Nanotube-modified electrodes present a surface area much higher than the bare glassy carbon surfaces as determined by capacitance measurements. Several redox probes were selected for checking the reactivity of specific sites at the carbon nanotube surface. The presence of carbon nanotubes on the electrode improves the kinetics for all the reactions studied compared with the bare glassy carbon electrode with variations of the heterogeneous electron transfer rate constant up to 5 orders of magnitude. The most important effects are observed for the benzoquinone/hydroquinone and ferrocene/ferricinium redox couples, which show a remarkable improvement of their electron transfer kinetics on SWCNT-modified electrodes, probably due to strong {pi}-{pi} interaction between the organic molecules and the walls of the carbon nanotubes. For many of the reactions studied, less than 1% of the nanotube-modified electrode surface is transferring charge to species in solution. This result suggests that only nanotube tips are active sites for the electron transfer in such cases. On the contrary, the electroactive surface for the reactions of ferrocene and quinone is higher indicating that the electron transfer is produced also from the nanotube walls.

Study on electroactive and electrocatalytic surfaces of single walled carbon nanotube-modified electrodes

International Nuclear Information System (INIS)

Salinas-Torres, David; Huerta, Francisco; Montilla, Francisco; Morallon, Emilia

2011-01-01

An investigation of the electrocatalysis of single-walled carbon nanotubes modified electrodes has been performed in this work. Nanotube-modified electrodes present a surface area much higher than the bare glassy carbon surfaces as determined by capacitance measurements. Several redox probes were selected for checking the reactivity of specific sites at the carbon nanotube surface. The presence of carbon nanotubes on the electrode improves the kinetics for all the reactions studied compared with the bare glassy carbon electrode with variations of the heterogeneous electron transfer rate constant up to 5 orders of magnitude. The most important effects are observed for the benzoquinone/hydroquinone and ferrocene/ferricinium redox couples, which show a remarkable improvement of their electron transfer kinetics on SWCNT-modified electrodes, probably due to strong π-π interaction between the organic molecules and the walls of the carbon nanotubes. For many of the reactions studied, less than 1% of the nanotube-modified electrode surface is transferring charge to species in solution. This result suggests that only nanotube tips are active sites for the electron transfer in such cases. On the contrary, the electroactive surface for the reactions of ferrocene and quinone is higher indicating that the electron transfer is produced also from the nanotube walls.

Selective association of outer surface lipoproteins with the lipid rafts of Borrelia burgdorferi.

Science.gov (United States)

Toledo, Alvaro; Crowley, Jameson T; Coleman, James L; LaRocca, Timothy J; Chiantia, Salvatore; London, Erwin; Benach, Jorge L

2014-03-11

Borrelia burgdorferi contains unique cholesterol-glycolipid-rich lipid rafts that are associated with lipoproteins. These complexes suggest the existence of macromolecular structures that have not been reported for prokaryotes. Outer surface lipoproteins OspA, OspB, and OspC were studied for their participation in the formation of lipid rafts. Single-gene deletion mutants with deletions of ospA, ospB, and ospC and a spontaneous gene mutant, strain B313, which does not express OspA and OspB, were used to establish their structural roles in the lipid rafts. All mutant strains used in this study produced detergent-resistant membranes, a common characteristic of lipid rafts, and had similar lipid and protein slot blot profiles. Lipoproteins OspA and OspB but not OspC were shown to be associated with lipid rafts by transmission electron microscopy. When the ability to form lipid rafts in live B. burgdorferi spirochetes was measured by fluorescence resonance energy transfer (FRET), strain B313 showed a statistically significant lower level of segregation into ordered and disordered membrane domains than did the wild-type and the other single-deletion mutants. The transformation of a B313 strain with a shuttle plasmid containing ospA restored the phenotype shared by the wild type and the single-deletion mutants, demonstrating that OspA and OspB have redundant functions. In contrast, a transformed B313 overexpressing OspC neither rescued the FRET nor colocalized with the lipid rafts. Because these lipoproteins are expressed at different stages of the life cycle of B. burgdorferi, their selective association is likely to have an important role in the structure of prokaryotic lipid rafts and in the organism's adaptation to changing environments. IMPORTANCE Lipid rafts are cholesterol-rich clusters within the membranes of cells. Lipid rafts contain proteins that have functions in sensing the cell environment and transmitting signals. Although selective proteins are present in

Geometric study of transparent superhydrophobic surfaces of molded and grid patterned polydimethylsiloxane (PDMS)

Science.gov (United States)

Davaasuren, Gaasuren; Ngo, Chi-Vinh; Oh, Hyun-Seok; Chun, Doo-Man

2014-09-01

Herein we describe an economical method to fabricate a transparent superhydrophobic surface that uses grid patterning, and we report on the effects of grid geometry in determining the wettability and transparency of the fabricated surfaces. A polymer casting method was utilized because of its applicability to economical manufacturing and mass production; the material polydimethylsiloxane (PDMS) was selected because of its moldability and transparency. PDMS was replicated from a laser textured mold fabricated by a UV nanosecond pulsed laser. Sapphire wafer was used for the mold because it has very low surface roughness (Ra ≤0.3 nm) and adequate mechanical properties. To study geometric effects, grid patterns of a series of step sizes were fabricated. The maximum water droplet contact angle (WDCA) observed was 171°. WDCAs depended on the wetting area and the wetting state. The experimental results of WDCA were analyzed with Wenzel and Cassie-Baxter equations. The designed grid pattern was suitably transparent and structurally stable. Transmittance of the optimal transparent superhydrophobic surface was measured by using a spectrophotometer. Transmittance loss due to the presence of the grid was around 2-4% over the wavelength region measured (300-1000 nm); the minimum transmittance observed was 83.1% at 300 nm. This study also demonstrates the possibility of using a nanosecond pulsed laser for the surface texturing of a superhydrophobic surface.

Site-selective substitutional doping with atomic precision on stepped Al (111) surface by single-atom manipulation.

Science.gov (United States)

Chen, Chang; Zhang, Jinhu; Dong, Guofeng; Shao, Hezhu; Ning, Bo-Yuan; Zhao, Li; Ning, Xi-Jing; Zhuang, Jun

2014-01-01

In fabrication of nano- and quantum devices, it is sometimes critical to position individual dopants at certain sites precisely to obtain the specific or enhanced functionalities. With first-principles simulations, we propose a method for substitutional doping of individual atom at a certain position on a stepped metal surface by single-atom manipulation. A selected atom at the step of Al (111) surface could be extracted vertically with an Al trimer-apex tip, and then the dopant atom will be positioned to this site. The details of the entire process including potential energy curves are given, which suggests the reliability of the proposed single-atom doping method.

Spectroscopic studies on surface reactions between minerals and reagents in flotation systems

International Nuclear Information System (INIS)

Giesekke, E.W.

1981-01-01

A study of the adsorbed species at the interface between the minerals and the aqueous solution is reported in the hope that it will contribute to a better understanding of selective mineral flotation by various reagents. The results of infrared spectroscopic studies are cited from the author's investigation on the fluorite-sodium oleate and fluorite-linoleate systems. Electron-spectroscopic techniques, e.g., electron spectroscopy for chemical analysis (ESCA) have also been useful in the identification of adsorbed species on mineral surfaces. Some experimental data from the literature are discussed. These studies have the disadvantage that they are not in situ investigations of the interface between the mineral and the aqueous solution. The potential use of other spectroscopic techniques are discussed, photo-acoustic, Raman, and electron-spin-resonance spectroscopy being considered as possible alternatives. It is suggested that the relatively small surface areas of minerals used in flotation (i.e. smaller than 2m 2 .g- 1 ) impose severe restrictions on the use of such techniques

Selective adsorption of benzhydroxamic acid on fluorite rendering selective separation of fluorite/calcite

Science.gov (United States)

Jiang, Wei; Gao, Zhiyong; Khoso, Sultan Ahmed; Gao, Jiande; Sun, Wei; Pu, Wei; Hu, Yuehua

2018-03-01

Fluorite, a chief source of fluorine in the nature, usually coexists with calcite mineral in ore deposits. Worldwide, flotation techniques with a selective collector and/or a selective depressant are commonly preferred for the separation of fluorite from calcite. In the present study, an attempt was made to use benzhydroxamic acid (BHA) as a collector for the selective separation of fluorite from calcite without using any depressant. Results obtained from the flotation experiments for single mineral and mixed binary minerals revealed that the BHA has a good selective collecting ability for the fluorite when 50 mg/L of BHA was used at pH of 9. The results from the zeta potential and X-ray photoelectron spectroscopy (XPS) indicated that the BHA easily chemisorbs onto the fluorite as compared to calcite. Crystal chemistry calculations showed the larger Ca density and the higher Ca activity on fluorite surface mainly account for the selective adsorption of BHA on fluorite, leading to the selective separation of fluorite from calcite. Moreover, a stronger hydrogen bonding with BHA and the weaker electrostatic repulsion with BHA- also contribute to the stronger interaction of BHA species with fluorite surface.

High Guanidinium Permeability Reveals Dehydration-Dependent Ion Selectivity in the Plasmodial Surface Anion Channel

Directory of Open Access Journals (Sweden)

Abdullah A. B. Bokhari

2014-01-01

Full Text Available Malaria parasites grow within vertebrate erythrocytes and increase host cell permeability to access nutrients from plasma. This increase is mediated by the plasmodial surface anion channel (PSAC, an unusual ion channel linked to the conserved clag gene family. Although PSAC recognizes and transports a broad range of uncharged and charged solutes, it must efficiently exclude the small Na+ ion to maintain infected cell osmotic stability. Here, we examine possible mechanisms for this remarkable solute selectivity. We identify guanidinium as an organic cation with high permeability into human erythrocytes infected with Plasmodium falciparum, but negligible uptake by uninfected cells. Transport characteristics and pharmacology indicate that this uptake is specifically mediated by PSAC. The rank order of organic and inorganic cation permeabilities suggests cation dehydration as the rate-limiting step in transport through the channel. The high guanidinium permeability of infected cells also allows rapid and stringent synchronization of parasite cultures, as required for molecular and cellular studies of this pathogen. These studies provide important insights into how nutrients and ions are transported via PSAC, an established target for antimalarial drug development.

Initial Reduction of CO2 on Pd-, Ru-, and Cu-Doped CeO2(111) Surfaces: Effects of Surface Modification on Catalytic Activity and Selectivity.

Science.gov (United States)

Guo, Chen; Wei, Shuxian; Zhou, Sainan; Zhang, Tian; Wang, Zhaojie; Ng, Siu-Pang; Lu, Xiaoqing; Wu, Chi-Man Lawrence; Guo, Wenyue

2017-08-09

Surface modification by metal doping is an effective treatment technique for improving surface properties for CO 2 reduction. Herein, the effects of doped Pd, Ru, and Cu on the adsorption, activation, and reduction selectivity of CO 2 on CeO 2 (111) were investigated by periodic density functional theory. The doped metals distorted the configuration of a perfect CeO 2 (111) by weakening the adjacent Ce-O bond strength, and Pd doping was beneficial for generating a highly active O vacancy. The analyses of adsorption energy, charge density difference, and density of states confirmed that the doped metals were conducive for enhancing CO 2 adsorption, especially for Cu/CeO 2 (111). The initial reductive dissociation CO 2 → CO* + O* on metal-doped CeO 2 (111) followed the sequence of Cu- > perfect > Pd- > Ru-doped CeO 2 (111); the reductive hydrogenation CO 2 + H → COOH* followed the sequence of Cu- > perfect > Ru- > Pd-doped CeO 2 (111), in which the most competitive route on Cu/CeO 2 (111) was exothermic by 0.52 eV with an energy barrier of 0.16 eV; the reductive hydrogenation CO 2 + H → HCOO* followed the sequence of Ru- > perfect > Pd-doped CeO 2 (111). Energy barrier decomposition analyses were performed to identify the governing factors of bond activation and scission along the initial CO 2 reduction routes. Results of this study provided deep insights into the effect of surface modification on the initial reduction mechanisms of CO 2 on metal-doped CeO 2 (111) surfaces.

A KINEMATIC STUDY OF FINSWIMMING AT SURFACE

Directory of Open Access Journals (Sweden)

Pier-Giorgio Zanone

2004-06-01

Full Text Available Finswimming is a sport of speed practiced on the surface or underwater, in which performance is based on whole-body oscillations. The present study investigated the undulatory motion performed by finswimmers at the surface. This study aiming to analyze the influence of the interaction of gender, practice level, and race distance on selected kinematic parameters. Six elite and six novices finswimmers equipped with joints markers (wrist, elbow, shoulder, hip, knee, and ankle were recorded in the sagittal plane. The position of these anatomical marks was digitized at 50 Hz. An automated motion analysis software yielded velocity, vertical amplitude, frequency, and angular position. Results showed that stroke frequency decreased whereas the mean amplitude of all joints increased with increasing race distance (p < 0.01. Mean joint amplitude for the upper limbs (wrist, elbow and shoulder was smaller for experts than for novices. Whereas that of the ankle was larger, so that the oscillation amplitude increased from shoulder to ankle. Elite male finswimmers were pitching more acutely than female. Moreover, elite male finswimmers showed a smaller knee bending than novices and than elite females (p < 0.01. This indicated that elite male finswimmers attempt to reduce drag forces thanks to a weak knee bending and a low upper limbs pitch. To sum up, gender, expertise, and race distance affect the performance and its kinematics in terms frontal drag. Expertise in finswimming requires taking advantage of the mechanical constraints pertaining to hydrodynamic constraints in order to optimize performance

A systematic first-principles study of surface energies, surface relaxation and Friedel oscillation of magnesium surfaces

International Nuclear Information System (INIS)

Tang, Jia-Jun; Yang, Xiao-Bao; Zhao, Yu-Jun; OuYang, LiuZhang; Zhu, Min

2014-01-01

We systematically study the surface energies and surface relaxations of various low-index and high-index Mg surfaces. It is found that low-index surfaces are not necessarily stable as Mg(1 0  1-bar  0) is the most unstable surface in the series of Mg(1 0  1-bar  n) (n = 0–9). A surface-energy predicting model based on the bond cutting is proposed to explain the relative surface stabilities. The local relaxations of the low-index surfaces could be explained by the Friedel oscillation. For the high-index surfaces, the combination of charge smoothing effect and dramatic charge depletion influences the relaxations, which show a big difference from the low-index ones. Our findings provide theoretical data for considerable insights into the surface energies of hexagonal close-packed metals. (paper)

Surface disinfection challenges for Candida auris: an in-vitro study.

Science.gov (United States)

Kean, R; Sherry, L; Townsend, E; McKloud, E; Short, B; Akinbobola, A; Mackay, W G; Williams, C; Jones, B L; Ramage, G

2018-04-01

The emerging pathogenic multidrug-resistant yeast Candida auris is an important source of healthcare-associated infections and of growing global clinical concern. The ability of this organism to survive on surfaces and withstand environmental stressors creates a challenge for eradicating it from hospitals. A panel of C. auris clinical isolates was evaluated on different surface environments against the standard disinfectant sodium hypochlorite and high-level disinfectant peracetic acid. C. auris was shown to selectively tolerate clinically relevant concentrations of sodium hypochlorite and peracetic acid in a surface-dependent manner, which may explain its ability to successfully persist within the hospital environment. Copyright © 2017 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.

Engineering the temporal response of photoconductive photodetectors via selective introduction of surface trap states.

Science.gov (United States)

Konstantatos, Gerasimos; Levina, Larissa; Fischer, Armin; Sargent, Edward H

2008-05-01

Photoconductive photodetectors fabricated using simple solution-processing have recently been shown to exhibit high gains (>1000) and outstanding sensitivities ( D* > 10(13) Jones). One ostensible disadvantage of exploiting photoconductive gain is that the temporal response is limited by the release of carriers from trap states. Here we show that it is possible to introduce specific chemical species onto the surfaces of colloidal quantum dots to produce only a single, desired trap state having a carefully selected lifetime. In this way we demonstrate a device that exhibits an attractive photoconductive gain (>10) combined with a response time ( approximately 25 ms) useful in imaging. We achieve this by preserving a single surface species, lead sulfite, while eliminating lead sulfate and lead carboxylate. In doing so we preserve the outstanding sensitivity of these devices, achieving a specific detectivity of 10(12) Jones in the visible, while generating a temporal response suited to imaging applications.

Direct evidence of ionic fluxes across ion-selective membranes: a scanning electrochemical microscopic and potentiometric study.

Science.gov (United States)

Gyurcsányi, R E; Pergel, E; Nagy, R; Kapui, I; Lan, B T; Tóth, K; Bitter, I; Lindner, E

2001-05-01

Scanning electrochemical microscopy (SECM) supplemented with potentiometric measurements was used to follow the time-dependent buildup of a steady-state diffusion layer at the aqueous-phase boundary of lead ion-selective electrodes (ISEs). Differential pulse voltammetry is adapted to SECM for probing the local concentration profiles at the sample side of solvent polymeric membranes. Major factors affecting the membrane transport-related surface concentrations were identified from SECM data and the potentiometric transients obtained under different experimental conditions (inner filling solution composition, membrane thickness, surface pretreatment). The amperometrically determined surface concentrations correlated well with the lower detection limits of the lead ion-selective electrodes.

Nuclear site selection studies

International Nuclear Information System (INIS)

Gharib, A.; Zohoorian Izadpanah, A.A.; Iranmanesh, H.

2000-01-01

It is of special importance, especially from the nuclear safety viewpoint, to select suitable sites for different nuclear structures with the considered future activities. Site selection sometimes involves high costs not necessarily for merely selecting of site but for some preliminary measures to be taken so as the site may have the necessary characteristics. The more suitable the natural characteristics of the site for the considered project, the more successful and efficient the project, the lower the project costs and the longer the project operation period. If so, the project will cause the growth of public culture and sustainable socioeconomic development. This paper is the result of the conclusion of numerous massive reports of this activity in the preliminary phase based on theories, practices and the related safety principles on this ground as well as the application of data and information of the past and a glance to the future. The conception of need for a site for medium structures and nuclear research projects and how to perform this process are presented step by step here with a scientific approach to its selection during the investigations. In this study, it is practically described how the site is selected, by determining and defining the characteristics of research and nuclear projects with medium structures and also its fitting to the optimum site. The discovered sites typically involve the best advantages in technical and economic aspects and no particular contrast with the concerned structures

Strategy for Ranking the Science Value of the Surface of Asteroid 101955 Bennu for Sample Site Selection for Osiris-REx

Science.gov (United States)

Nakamura-Messenger, K.; Connolly, H. C., Jr.; Lauretta, D. S.

2014-01-01

OSRIS-REx is NASA's New Frontiers 3 sample return mission that will return at least 60 g of pristine surface material from near-Earth asteroid 101955 Bennu in September 2023. The scientific value of the sample increases enormously with the amount of knowledge captured about the geological context from which the sample is collected. The OSIRIS-REx spacecraft is highly maneuverable and capable of investigating the surface of Bennu at scales down to the sub-cm. The OSIRIS-REx instruments will characterize the overall surface geology including spectral properties, microtexture, and geochemistry of the regolith at the sampling site in exquisite detail for up to 505 days after encountering Bennu in August 2018. The mission requires at the very minimum one acceptable location on the asteroid where a touch-and-go (TAG) sample collection maneuver can be successfully per-formed. Sample site selection requires that the follow-ing maps be produced: Safety, Deliverability, Sampleability, and finally Science Value. If areas on the surface are designated as safe, navigation can fly to them, and they have ingestible regolith, then the scientific value of one site over another will guide site selection.

A density gradient of VAPG peptides on a cell-resisting surface achieves selective adhesion and directional migration of smooth muscle cells over fibroblasts.

Science.gov (United States)

Yu, Shan; Zuo, Xingang; Shen, Tao; Duan, Yiyuan; Mao, Zhengwei; Gao, Changyou

2018-05-01

Selective adhesion and migration of smooth muscle cells (SMCs) over fibroblasts (FIBs) is required to prevent adventitia fibrosis in vascular regeneration. In this study, a uniform cell-resisting layer of poly(ethylene glycol) (PEG) with a density gradient of azide groups was generated on a substrate by immobilizing two kinds of PEG molecules in a gradient manner. A density gradient of alkynyl-functionalized Val-Ala-Pro-Gly (VAPG) peptides was then prepared on the PEG layer via click chemistry. The VAPG density gradient was characterized by fluorescence imaging, revealing the gradual enhancement of the fluorescent intensity along the substrate direction. The adhesion and mobility of SMCs were selectively enhanced on the VAPG density gradient, leading to directional migration toward the higher peptide density (up to 84%). In contrast, the adhesion and mobility of FIBs were significantly weakened. The net displacement of SMCs also significantly increased compared with that on tissue culture polystyrene (TCPS) and that of FIBs on the gradient. The mitogen-activated protein kinase (MAPK) signaling pathways related to cell migration were studied, showing higher expressions of functional proteins from SMCs on the VAPG-modified surface in a density-dependent manner. For the first time the selective adhesion and directional migration of SMCs over FIBs was achieved by an elaborative design of a gradient surface, leading to a new insight in design of novel vascular regenerative materials. Selective cell adhesion and migration guided by regenerative biomaterials are extremely important for the regeneration of targeted tissues, which can avoid the drawbacks of incorrect and uncontrolled responses of tissue cells to implants. For example, selectivity of smooth muscle cells (SMCs) over fibroblasts (FIBs) is required to prevent adventitia fibrosis in vascular regeneration. Herein we prepare a uniform cell-repelling layer, on which SMCs-selective Val-Ala-Pro-Gly (VAPG) peptides

Studies on Gas Sensing Performance of Pure and Surface Modified SrTiO3 Thick Film Resistors

Directory of Open Access Journals (Sweden)

V. B. Gaikwad

2009-08-01

Full Text Available Strontium Titanate (SrTiO3 (ST was prepared mechanochemically from Sr(OH2 and TiO2. XRD confirms the Perovskite phase of material. Thick films of ST were prepared by screen-printing technique. The gas sensing performances of thick films were tested for various gases. It showed maximum sensitivity to CO gas at 350 oC for 100 ppm gas concentration. To improve the sensitivity and selectivity of the film towards a particular gas, ST thick films were surface modified by dipping them in a solution of nano copper for different intervals of time. These surface modified ST films showed larger sensitivity to H2S gas (100 ppm at 300 oC than pure ST film. A systematic study, of sensing performance of the sensor, indicates the key role-played by the nano copper species on the surface .The sensitivity, selectivity, response and recovery time of the sensor were measured and presented.

Selective surface oxidation and segregation upon short term annealing of model alloys and industrial steel grades

Energy Technology Data Exchange (ETDEWEB)

Swaminathan, S.

2007-07-01

Segregation and selective oxidation phenomena of minor alloying elements during annealing of steel sheets lead to the formation of bare spots after hot-dip galvanizing. This thesis highlights the influence of annealing conditions and the effect of alloying elements on the selective oxidation in model alloys and some industrial steel grades. Model alloys of binary (Fe-2Si, Fe-2Mn, Fe-0.8Cr), ternary (Fe-2Mn-2Si, Fe-2Mn-0.8Cr, Fe-1Mn-0.8Cr, Fe-1Si-0.8Cr, Fe-2Si-0.8Cr) and quarternary (Fe-2Mn-2Si-0.8Cr) systems were studied. In the case of steels, standard grade interstitial free (IF) steels and experimental grade tensile strength 1000 MPa steel were investigated. All specimens were annealed at 820 C in N{sub 2}-5%H{sub 2} gas atmospheres with the wide range of dew points (i.e. -80 to 0 C). The surface chemistry after annealing and its wettability with liquid Zn have been correlated as a function of dew points by simulating the hot-dip galvanizing process at laboratory scale. (orig.)

Tip-Selective Growth of Silver on Gold Nanostars for Surface-Enhanced Raman Scattering.

Science.gov (United States)

Zhang, Weiqing; Liu, Jie; Niu, Wenxin; Yan, Heng; Lu, Xianmao; Liu, Bin

2018-04-19

Nanogaps as "hot spots" with highly localized surface plasmon can generate ultrastrong electromagnetic fields. Superior to the exterior nanogaps obtained via aggregation and self-assembly, interior nanogaps within Au and Ag nanostructures give stable and reproducible surface-enhanced Raman scattering (SERS) signals. However, the synthesis of nanostructures with interior hot spots is still challenging because of the lack of high-yield strategies and clear design principles. Herein, gold-silver nanoclusters (Au-Ag NCs) with multiple interior hot spots were fabricated as SERS platforms via selective growth of Ag nanoparticles on the tips of Au nanostars (Au NSs). Furthermore, the interior gap sizes of Au-Ag NCs can be facilely tuned by changing the amount of AgNO 3 used. Upon 785 nm excitation, single Au-Ag NC 350 exhibits 43-fold larger SERS enhancement factor and the optimal signal reproducibility relative to single Au NS. The SERS enhancement factors and signal reproducibility of Au-Ag NCs increase with the decrease of gap sizes. Collectively, the Au-Ag NCs could serve as a flexible, reproducible, and active platform for SERS investigation.

Effect of input power and gas pressure on the roughening and selective etching of SiO2/Si surfaces in reactive plasmas

International Nuclear Information System (INIS)

Zhong, X. X.; Huang, X. Z.; Tam, E.; Ostrikov, K.; Colpo, P.; Rossi, F.

2010-01-01

We report on the application low-temperature plasmas for roughening Si surfaces which is becoming increasingly important for a number of applications ranging from Si quantum dots to cell and protein attachment for devices such as 'laboratory on a chip' and sensors. It is a requirement that Si surface roughening is scalable and is a single-step process. It is shown that the removal of naturally forming SiO 2 can be used to assist in the roughening of the surface using a low-temperature plasma-based etching approach, similar to the commonly used in semiconductor micromanufacturing. It is demonstrated that the selectivity of SiO 2 /Si etching can be easily controlled by tuning the plasma power, working gas pressure, and other discharge parameters. The achieved selectivity ranges from 0.4 to 25.2 thus providing an effective means for the control of surface roughness of Si during the oxide layer removal, which is required for many advance applications in bio- and nanotechnology.

Rapid and selective adsorption of cationic dyes by a unique metal-organic framework with decorated pore surface

Science.gov (United States)

Zhang, Jie; Li, Fan; Sun, Qian

2018-05-01

Organic dye pollutants become a big headache due to their toxic nature to the environment, and it should be one of the best solutions if we can remove and separate them. Here, a metal-organic framework (MOF) (denoted as Zn-MOF) with carbonyl group based on fluorenone-2,7-dicarboxylate ligand, was directly synthesized without post-synthesis method and applied to selectively absorb cationic dyes such as MB, CV, RhB from aqueous solution, while anionic or neutral dyes were excluded. Characterization of the Zn-MOF was achieved by X-ray diffraction, scanning electron microscope, Fourier transform infrared spectrometry and elemental analysis. The Zn-MOF mainly possesses open pore channels, high surface area, big pore volume, and most important, the pore surface is furnished with carbonyl groups arising from the ligand and pointing toward the centers of the large chambers of the framework, which are benefit for the adsorption of the cationic dyes. The MB maximum adsorption capacities can attain 326 mg g-1, which is probably due to the suitable pore size, higher solvent-accessible void, and the prominent adsorption capacity of the mesoporous material. The dye adsorption process for the material is proven to be charge-selective and size-selective, and the adsorption isotherms, as well as kinetics characteristic of dye adsorption onto the Zn-MOF were also investigated.

AOAC Official MethodSM Matrix Extension Validation Study of Assurance GDSTM for the Detection of Salmonella in Selected Spices.

Science.gov (United States)

Feldsine, Philip; Kaur, Mandeep; Shah, Khyati; Immerman, Amy; Jucker, Markus; Lienau, Andrew

2015-01-01

Assurance GDSTM for Salmonella Tq has been validated according to the AOAC INTERNATIONAL Methods Committee Guidelines for Validation of Microbiological Methods for Food and Environmental Surfaces for the detection of selected foods and environmental surfaces (Official Method of AnalysisSM 2009.03, Performance Tested MethodSM No. 050602). The method also completed AFNOR validation (following the ISO 16140 standard) compared to the reference method EN ISO 6579. For AFNOR, GDS was given a scope covering all human food, animal feed stuff, and environmental surfaces (Certificate No. TRA02/12-01/09). Results showed that Assurance GDS for Salmonella (GDS) has high sensitivity and is equivalent to the reference culture methods for the detection of motile and non-motile Salmonella. As part of the aforementioned validations, inclusivity and exclusivity studies, stability, and ruggedness studies were also conducted. Assurance GDS has 100% inclusivity and exclusivity among the 100 Salmonella serovars and 35 non-Salmonella organisms analyzed. To add to the scope of the Assurance GDS for Salmonella method, a matrix extension study was conducted, following the AOAC guidelines, to validate the application of the method for selected spices, specifically curry powder, cumin powder, and chili powder, for the detection of Salmonella.

Facile spray-coating process for the fabrication of tunable adhesive superhydrophobic surfaces with heterogeneous chemical compositions used for selective transportation of microdroplets with different volumes.

Science.gov (United States)

Li, Jian; Jing, Zhijiao; Zha, Fei; Yang, Yaoxia; Wang, Qingtao; Lei, Ziqiang

2014-06-11

In this paper, tunable adhesive superhydrophobic ZnO surfaces have been fabricated successfully by spraying ZnO nanoparticle (NP) suspensions onto desired substrates. We regulate the spray-coating process by changing the mass percentage of hydrophobic ZnO NPs (which were achieved by modifying hydrophilic ZnO NPs with stearic acid) in the hydrophobic/hydrophilic ZnO NP mixtures to control heterogeneous chemical composition of the ZnO surfaces. Thus, the water adhesion on the same superhydrophobic ZnO surface could be effectively tuned by controlling the surface chemical composition without altering the surface morphology. Compared with the conventional tunable adhesive superhydrophobic surfaces, on which there were only three different water sliding angle values: lower than 10°, 90° (the water droplet is firmly pinned on the surface at any tilted angles), and the value between the two ones, the water adhesion on the superhydrophobic ZnO surfaces has been tuned effectively, on which the sliding angle is controlled from 2 ± 1° to 9 ± 1°, 21 ± 2°, 39 ± 3°, and 90°. Accordingly, the adhesive force can be adjusted from extremely low (∼2.5 μN) to very high (∼111.6 μN). On the basis of the different adhesive forces of the tunable adhesive superhydrophobic surfaces, the selective transportation of microdroplets with different volumes was achieved, which has never been reported before. In addition, we demonstrated a proof of selective transportation of microdroplets with different volumes for application in the droplet-based microreactors via our tunable adhesive superhydrophobic surfaces for the quantitative detection of AgNO3 and NaOH. The results reported herein realize the selective transportation of microdroplets with different volumes and we believe that this method would potentially be used in many important applications, such as selective water droplet transportation, biomolecular quantitative detection and droplet-based biodetection.

A Socio-Semantic Study of Selected Nicknames Used by Yoruba Brides for In-Laws

Directory of Open Access Journals (Sweden)

Adebola Adebileje

2012-11-01

Full Text Available This study aims at describing the socio-semantic characteristics of twelve selected nicknames used by Yoruba brides for their in-laws. The data for the study was collected through observation, structured interview and review of literature. The collected nicknames were described and classified according to Halliday’s theory of context in order to get contextual meanings of the selected nicknames. Comparison between lexical and contextual meanings of the nicknames was provided based on the cultural background of Yoruba brides and results revealed that 58% of selected nicknames coined by brides compliment in-laws, 17% are derogatory and 25% assume the dual functions of being compliments and insults. In addition, nicknames’ meanings reveal the type of relationship that exists between the bride and her in-laws as the surface meanings of nicknames sometimes may not be the same as the meanings intended by the bride. It is recommended that this culture in Yoruba marriage should be encouraged among modern Yoruba youths who seem to have neglected it.

Wetting study of patterned surfaces for superhydrophobicity

Energy Technology Data Exchange (ETDEWEB)

Bhushan, Bharat [Nanotribology Laboratory for Information Storage and MEMS/NEMS (NLIM), 201 W. 19th Avenue, Ohio State University, Columbus, OH 43202-1107 (United States)], E-mail: Bhushan.2@osu.edu; Jung, Yong Chae [Nanotribology Laboratory for Information Storage and MEMS/NEMS (NLIM), 201 W. 19th Avenue, Ohio State University, Columbus, OH 43202-1107 (United States)

2007-10-15

Superhydrophobic surfaces have considerable technological potential for various applications due to their extreme water-repellent properties. A number of studies have been carried out to produce artificial biomimetic roughness-induced hydrophobic surfaces. In general, both homogeneous and composite interfaces are possible on the produced surface. Silicon surfaces patterned with pillars of two different diameters and heights with varying pitch values were fabricated. We show how static contact angles vary with different pitch values on the patterned silicon surfaces. Based on the experimental data and a numerical model, the trends are explained. We show that superhydrophobic surfaces have low hysteresis and tilt angle. Tribological properties play an important role in many applications requiring water-repellent properties. Therefore, it is important to study the adhesion and friction properties of these surfaces that mimic nature. An atomic/friction force microscope (AFM/FFM) is used for surface characterization and adhesion and friction measurements.

Piperidine adsorption on two different silver electrodes: A combined surface enhanced Raman spectroscopy and density functional theory study

International Nuclear Information System (INIS)

Hao Yanling; Fang Yan

2007-01-01

The surface enhanced Raman scattering (SERS) spectra of piperidine in silver colloid solution, on roughened silver electrode and on roughened silver electrode modified with silver nanoparticles were studied, and the high-quality SERS spectra of piperidine on roughened silver electrode modified with silver nanoparticles were obtained for the first time. Surface selection rules derived from the EM enhancement model were employed to deduce piperidine orientations on the different surfaces. On the basis of this, two models of piperidine adsorbed on the surface of the silver nanoparticles were built, and DFT-B3PW91/LanL2dz was applied to calculate the Raman frequencies. It proves that, at higher potential values, the piperidine is perpendicularly standing on the roughened silver electrode surface though its lone-electron pair, but in silver colloid solution and on the silver nanoparticles modified silver electrode the piperidine molecular lies flat on the silver surface. In the meantime, the potential dependent SERS of piperidine on the modified electrode were studied

Deposition of size-selected atomic clusters on surfaces

International Nuclear Information System (INIS)

Carroll, S.J.

1999-06-01

This dissertation presents technical developments and experimental and computational investigations concerned with the deposition of atomic clusters onto surfaces. It consists of a collection of papers, in which the main body of results are contained, and four chapters presenting a subject review, computational and experimental techniques and a summary of the results presented in full within the papers. Technical work includes the optimization of an existing gas condensation cluster source based on evaporation, and the design, construction and optimization of a new gas condensation cluster source based on RF magnetron sputtering (detailed in Paper 1). The result of cluster deposition onto surfaces is found to depend on the cluster deposition energy; three impact energy regimes are explored in this work. (1) Low energy: n clusters create a defect in the surface, which pins the cluster in place, inhibiting cluster diffusion at room temperature (Paper V). (3) High energy: > 50 eV/atom. The clusters implant into the surface. For Ag 20 -Ag 200 clusters, the implantation depth is found to scale linearly with the impact energy and inversely with the cross-sectional area of the cluster, with an offset due to energy lost to the elastic compression of the surface (Paper VI). For smaller (Ag 3 ) clusters the orientation of the cluster with respect to the surface and the precise impact site play an important role; the impact energy has to be 'focused' in order for cluster implantation to occur (Paper VII). The application of deposited clusters for the creation of Si nanostructures by plasma etching is explored in Paper VIII. (author)

The bioavailability of the transuranic elements 237Pu and 241Am for the pond snail, Lymnaea stagnalis L., and their behaviour in selected natural surface waters

International Nuclear Information System (INIS)

Thiels, G.M.

1983-01-01

An attempt was made to characterise the bioavailability of 237 Pu and 241 Am for the pond snail Lymnaea stagnalis L. in selected surface waters. The uptake, distribution and retention patterns were studied through the contamination route water-snail. The effects of a number of parameters, such as seasonal variation, water type (pH, conductivity, ionic composition) and presence of food, on the bioavailability of the transuranics were evaluated. Finally, an assessment was made concerning the chemical speciation of plutonium and americium in the selected freshwaters

Selective Dispersive Solid Phase Extraction of Ser-traline Using Surface Molecularly Imprinted Polymer Grafted on SiO2/Graphene Oxide

Directory of Open Access Journals (Sweden)

Faezeh Khalilian

2017-01-01

Full Text Available A surface molecularly imprinted dispersive solid phase extraction coupled with liquid chromatography–ultraviolet detection is proposed as a selective and fast clean-up technique for the determination of sertraline in biological sample. Surface sertraline-molecular imprinted polymer was grafted and synthesized on the SiO2/graphene oxide surface. Firstly SiO2 was coated on synthesized graphene oxide sheet using sol-gel technique. Prior to polymerization, the vinyl group was incorporated on to the surface of SiO2/graphene oxide to direct selective polymerization on the surface. Methacrylic acid, ethylene glycol dimethacrylate and ethanol were used as monomer, cross-linker and progen, respectively. Non-imprinted polymer was also prepared for comparing purposes. The properties of the molecular imprinted polymer were characterized using field emission-scanning electron microscopy and Fourier transform infrared spectroscopy methods. The surface molecular imprinted polymer was utilized as an adsorbent of dispersive solid phase extraction for separation and preconcentration of sertraline. The effects of the different parameters influencing the extraction efficiency, such as sample pH were investigated and optimized. The specificity of the molecular imprinted polymer over the non-imprinted polymer was examined in absence and presence of competitive drugs. Sertraline calibration curve showed linearity in the ranges 1–500 µg L-1. The limits of detection and quantification under optimized conditions were obtained 0.2 and 0.5 µg L-1. The within-day and between-day relative standard deviations (n=3 were 4.3 and 7.1%, respectively. Furthermore, the relative recoveries for spiked biological samples were above 92%.

Copper circuit patterning on polymer using selective surface modification and electroless plating

Energy Technology Data Exchange (ETDEWEB)

Park, Sang Jin [Department of Materials Science and Engineering, Chungnam National University, Daejeon 305-764 (Korea, Republic of); Ko, Tae-Jun [Institute for Multidisciplinary Convergence of Materials, Korea Institute of Science and Technology, Seoul 130-650 (Korea, Republic of); Department of Materials Science and Engineering, Seoul National University, Seoul 151-742 (Korea, Republic of); Yoon, Juil [Department of Mechanical Systems Engineering, Hansung University, Seoul 136-792 (Korea, Republic of); Moon, Myoung-Woon [Institute for Multidisciplinary Convergence of Materials, Korea Institute of Science and Technology, Seoul 130-650 (Korea, Republic of); Oh, Kyu Hwan [Department of Materials Science and Engineering, Seoul National University, Seoul 151-742 (Korea, Republic of); Han, Jun Hyun, E-mail: jhhan@cnu.ac.kr [Department of Materials Science and Engineering, Chungnam National University, Daejeon 305-764 (Korea, Republic of)

2017-02-28

Highlights: • A new simple two step method for the pattering of Cu circuits on PET substrate was proposed. • The simple patterning of the high adhesive Cu circuits was achieved by plasma treatment using a patterned mask coated with a catalyst material. • The high adhesive strength of Cu circuits was due to the nanostructure formed by oxygen plasma treatment. - Abstract: We have examined a potential new and simple method for patterning a copper circuit on PET substrate by copper electroless plating, without the pretreatment steps (i.e., sensitization and activation) for electroless plating as well as the etching processes of conventional circuit patterning. A patterned mask coated with a catalyst material, Ag, for the reduction of Cu ions, is placed on a PET substrate. Subsequent oxygen plasma treatment of the PET substrate covered with the mask promotes the selective generation of anisotropic pillar- or hair-like nanostructures coated with co-deposited nanoparticles of the catalyst material on PET. After oxygen plasma treatment, a Cu circuit is well formed just by dipping the plasma-treated PET into a Cu electroless plating solution. By increasing the oxygen gas pressure in the chamber, the height of the nanostructures increases and the Ag catalyst particles are coated on not only the top but also the side surfaces of the nanostructures. Strong mechanical interlocking between the Cu circuit and PET substrate is produced by the large surface area of the nanostructures, and enhances peel strength. Results indicate this new simple two step (plasma surface modification and pretreatment-free electroless plating) method can be used to produce a flexible Cu circuit with good adhesion.

Digital surfaces and thicknesses of selected hydrogeologic units of the Floridan aquifer system in Florida and parts of Georgia, Alabama, and South Carolina

Science.gov (United States)

Williams, Lester J.; Dixon, Joann F.

2015-01-01

Digital surfaces and thicknesses of selected hydrogeologic units of the Floridan aquifer system were developed to define an updated hydrogeologic framework as part of the U.S. Geological Survey Groundwater Resources Program. The dataset contains structural surfaces depicting the top and base of the aquifer system, its major and minor hydrogeologic units and zones, geophysical marker horizons, and the altitude of the 10,000-milligram-per-liter total dissolved solids boundary that defines the approximate fresh and saline parts of the aquifer system. The thicknesses of selected major and minor units or zones were determined by interpolating points of known thickness or from raster surface subtraction of the structural surfaces. Additional data contained include clipping polygons; regional polygon features that represent geologic or hydrogeologic aspects of the aquifers and the minor units or zones; data points used in the interpolation; and polygon and line features that represent faults, boundaries, and other features in the aquifer system.

High-resolution electron-energy-loss spectroscopy studies of clean and hydrogen-covered tungsten (100) surfaces

International Nuclear Information System (INIS)

Woods, J.P.

1986-01-01

High-resolution (10-meV FWHM) low-energy (≤ 100eV) electrons are scattered from the tungsten (100) surface. Electron-energy-loss spectroscopy (EELS) selection rules are utilized to identify vibrational modes of the surface tungsten atoms. A 36-meV mode is measured on the c(2 X 2) thermally reconstructed surface and is modeled as an overtone of the 18-meV mode at M in the surface Brillouin zone. The superstructure of the reconstructed surface allows this mode to be observed in specular scattering. The surface tungsten atoms return to their bulk lateral positions with saturated hydrogen (β 1 phase) adsorption; and a 26-meV mode identified is due to the perpendicular vibration of the surface tungsten layers. The clean-room temperature surface does not display either low-energy vibrations and the surface is modeled as disordered. The three β 1 phase hydrogen vibrations are observed and a new vibration at 118 meV is identified. The 118-meV cross section displays characteristics of a parallel mode, but calculations show this assignment to be erroneous. There are two hydrogen atoms for each surface tungsten atom in the β 1 phase, and lattice-dynamical calculations show that the 118-meV mode is due to a hydrogen-zone edge vibration. The predicted breakdown of the parallel hydrogen vibration selection rule was not observed

Improving catalytic selectivity through control of adsorption orientation

Science.gov (United States)

Pang, Simon H.

In this thesis, we present an investigation, starting from surface science experiments, leading to design of supported catalysts, of how adsorption orientation can be used to affect reaction selectivity of highly functional molecules. The surface chemistry of furfuryl alcohol and benzyl alcohol and their respective aldehydes was studied on a Pd(111) single-crystal surface under ultra-high vacuum conditions. Temperature-programmed desorption experiments showed that synergistic chemistry existed between the aromatic ring and the oxygen-containing functional group, each allowing the other to participate in reaction pathways that a monofunctional molecule could not. Most important of these was a deoxygenation reaction that occurred more readily when the surface was crowded by the highest exposures. High-resolution electron energy loss spectroscopy revealed that at these high exposures, molecules were oriented upright on the surface, with the aromatic function extending into vacuum. In contrast, at low exposures, molecules were oriented flat on the surface. The upright adsorption geometry was correlated with deoxygenation, whereas the flat-lying geometry was correlated with decarbonylation. The insight gained from surface science experiments was utilized in catalyst design. Self-assembled monolayers of alkanethiolates were used to systematically reduce the average surface ensemble size, and the reaction selectivity was tracked. When a sparsely-packed monolayer was used, such as one formed by 1-adamantanethiol, the reactant furfural was still able to lie flat on the surface and the reaction selectivity was similar to that of the uncoated catalyst. However, when a densely-packed monolayer, formed by 1-octadecanethiol, was used, furfural was not able to adsorb flat on the surface and instead adopted an upright conformation, leading to a drastic increase in aldehyde hydrogenation and hydrodeoxygenation reaction selectivity. Using an even higher sulfur coverage from a

Selective solid-phase extraction of Hg(II) using silica gel surface - imprinting technique

International Nuclear Information System (INIS)

Zheng, H.; Geng, T.; Hu, L.

2008-01-01

A new ion-imprinted amino-functionalized silica gel sorbent was synthesized by surface-imprinting technique for preconcentration and separation of Hg(II) prior to its determination by inductively coupled plasma optical emission spectrometry (ICP-OES). Compared to the traditional solid sorbents and non-imprinted polymer particles, the ion-imprinted polymers (IIPs) have higher adsorption capacity and selectivity for Hg(II). The maximum static adsorption capacity of the imprinted and non-imprinted sorbent for Hg(II) was 29.89 mg g -1 and 11.21 mg g -1 , respectively. The highest selectivity coefficient for Hg(II) in the presence of Zn(II) exceeded 230. The detection limit (3σ) of the method was 0.25 μg L -1 . The relative standard deviation of the method was 2.5% for eight replicate determinations of 10 μg of Hg 2+ in 200 mL-in-volume water sample. The procedure was validated by performing the analysis of the certified river sediment sample (GBW 08603, China) using the standard addition method. The developed method was also successfully applied to the determination of trace mercury in Chinese traditional medicine and water samples with satisfactory results. (authors)

Groundwater-surface water relations in the Fox River watershed: insights from exploratory studies in Illinois and Wisconsin

Science.gov (United States)

Mills, Patrick C.

2014-01-01

Exploratory studies were conducted at sites bordering the Fox River in Waukesha, Wisconsin, during 2010 and McHenry, Illinois, during 2011–13. The objectives of the studies were to assess strategies for the study of and insights into the potential for directly connected groundwater and surface-water systems with natural groundwater discharge to streams diverted and (or) streamflow induced (captured) by nearby production-well withdrawals. Several collection efforts of about 2 weeks or less provided information and data on site geology, groundwater and surface-water levels, hydraulic gradients, water-temperature and stream-seepage patterns, and water chemistry including stables isotopes. Overview information is presented for the Waukesha study, and selected data and preliminary findings are presented for the McHenry study.

Surface studies with high-energy ion beams

Energy Technology Data Exchange (ETDEWEB)

Stensgaard, Ivan [Aarhus Univ. (Denmark). Inst. of Physics

1992-07-01

High-energy ion scattering is an extremely useful technique for surface studies. Three methods for surface composition analysis (Rutherford backscattering, nuclear-reaction analysis and elastic recoil detection) are discussed. Directional effects in ion-beam surface interactions (shadowing and blocking) form the basis for surface structure analysis with high-energy ion beams and these phenomena are addressed in some detail. It is shown how surface relaxation and reconstruction, as well as positions of adsorbed atoms, can be determined by comparison with computer simulations. A special technique called transmission channelling is introduced and shown to be particularly well suited for studies of adsorption positions, even of hydrogen. Recent developments in the field are demonstrated by discussing a large number of important (experimental) applications which also include surface dynamics and melting, as well as epitaxy and interface structure. (author).

A pulsed source neutron reflectometer for surface studies

International Nuclear Information System (INIS)

Penfold, J.; Williams, W.G.

1985-05-01

A design for a neutron reflectometer for surface studies to be constructed at the SNS is presented. Examples of its use to study problems in surface chemistry, surface magnetism and low dimensional structures are highlighted. (author)

CuO-PANI nanostructure with tunable spectral selectivity for solar selective coating application

Energy Technology Data Exchange (ETDEWEB)

Cindrella, L., E-mail: cind@nitt.edu; Prabhu, S., E-mail: sprabhuk@gmail.com

2016-08-15

Highlights: • CuO-PANI nanostructure has been reported as the solar selective absorber coating. • Solar selectivity and efficiency of the coatings have been evaluated. • PANI provides a surface texture favourable for multiple reflection. - Abstract: CuO-PANI nanostructure has been demonstrated as the solar selective absorber coating for the first time. The effortless chemical methods and easily scalable techniques such as precipitation, in-situ polymerization and spray coating were adopted for the fabrication of CuO nanorods and CuO-PANI nanostructures for solar application. The synthesis was carried out without using any template. The morphology and phase structure of fabricated CuO nanorods and CuO-PANI nanostructure coatings were studied by atomic force microscopy, scanning electron microscopy and X-ray diffraction analysis. The energy dispersive X-ray spectra and elemental mapping confirm the presence of the chosen elements in the nanostructure. The solar absorptance (α{sub s}), thermal emittance (ε{sub t}) and selectivity (ξ) of the nanostructure coatings on glass substrate were optimized to 0.94, 0.01 and 94 respectively by changing the polyaniline content on the surface of the CuO nanorods. The efficiency of the solar selective coatings were evaluated. The optimized solar absorber coating of CuO-PANI nanostructure is highly promising for its selective optical properties.

Modeling Surface Roughness to Estimate Surface Moisture Using Radarsat-2 Quad Polarimetric SAR Data

Science.gov (United States)

Nurtyawan, R.; Saepuloh, A.; Budiharto, A.; Wikantika, K.

2016-08-01

Microwave backscattering from the earth's surface depends on several parameters such as surface roughness and dielectric constant of surface materials. The two parameters related to water content and porosity are crucial for estimating soil moisture. The soil moisture is an important parameter for ecological study and also a factor to maintain energy balance of land surface and atmosphere. Direct roughness measurements to a large area require extra time and cost. Heterogeneity roughness scale for some applications such as hydrology, climate, and ecology is a problem which could lead to inaccuracies of modeling. In this study, we modeled surface roughness using Radasat-2 quad Polarimetric Synthetic Aperture Radar (PolSAR) data. The statistical approaches to field roughness measurements were used to generate an appropriate roughness model. This modeling uses a physical SAR approach to predicts radar backscattering coefficient in the parameter of radar configuration (wavelength, polarization, and incidence angle) and soil parameters (surface roughness and dielectric constant). Surface roughness value is calculated using a modified Campbell and Shepard model in 1996. The modification was applied by incorporating the backscattering coefficient (σ°) of quad polarization HH, HV and VV. To obtain empirical surface roughness model from SAR backscattering intensity, we used forty-five sample points from field roughness measurements. We selected paddy field in Indramayu district, West Java, Indonesia as the study area. This area was selected due to intensive decreasing of rice productivity in the Northern Coast region of West Java. Third degree polynomial is the most suitable data fitting with coefficient of determination R2 and RMSE are about 0.82 and 1.18 cm, respectively. Therefore, this model is used as basis to generate the map of surface roughness.

Energy loss spectroscopy applied to surface studies

International Nuclear Information System (INIS)

Lecante, J.

1975-01-01

The analysis of energy losses suffered by slow electrons (5eV to 300eV) back-scattered by single crystal surfaces appears to be a powerful method for surfaces studies. The inelastic scattering of these slow electrons limits their escape depth to the surface region. After a review of the basic excitation processes due to the interaction between electrons and surfaces (phonons, plasmons and electronic transitions) a brief discussion is given about the instruments needed for this electrons spectroscopy. Finally some experimental results are listed and it is shown that the comparison of the results given by ELS with other surface sensitive methods such as UPS is very fruitful and new information can be obtained. The improvement of theoretical studies on surface excitations due to slow electrons will provide in the next future the possibility of analysing in a more quantitative way the results given by ELS [fr

A novel typing method for Streptococcus pneumoniae using selected surface proteins

Directory of Open Access Journals (Sweden)

Arnau eDomenech

2016-03-01

Full Text Available The diverse pneumococcal diseases are associated with different pneumococcal lineages, or clonal complexes. Nevertheless, intra-clonal genomic variability, which influences pathogenicity, has been reported for surface virulence factors. These factors constitute the communication interface between the pathogen and its host and their corresponding genes are subjected to strong selective pressures affecting functionality and immunogenicity. First, the presence and allelic dispersion of 97 outer protein families were screened in 19 complete pneumococcal genomes. Seventeen families were deemed variable and were then examined in 216 draft genomes. This procedure allowed the generation of binary vectors with 17 positions and the classification of strains into surfotypes. They represent the outer protein subsets with the highest inter-strain discriminative power. A total of 116 non-redundant surfotypes were identified. Those sharing a critical number of common protein features were hierarchically clustered into 18 surfogroups. Most clonal complexes with comparable epidemiological characteristics belonged to the same or similar surfogroups. However, the very large CC156 clonal complex was dispersed over several surfogroups. In order to establish a relationship between surfogroup and pathogenicity, the surfotypes of 95 clinical isolates with different serogroup/serotype combinations were analysed. We found a significant correlation between surfogroup and type of pathogenic behaviour (primary invasive, opportunistic invasive and non-invasive. We conclude that the virulent behaviour of S. pneumoniae is related to the activity of collections of, rather than individual, surface virulence factors. Since surfotypes evolve faster than MLSTs and directly reflect virulence potential, this novel typing protocol is appropriate for the identification of emerging clones.

Study of surface functionalization on IDE by using 3-aminopropyl triethoxysilane (APTES) for cervical cancer detection

Science.gov (United States)

Raqeema, S.; Hashim, U.; Azizah, N.

2016-07-01

This paper presented the study of surface functionalization on IDE by using 3-Aminopropyl triethoxysilane (APTES). The DNA nanochip based interdigitated (IDE) has been proposed to optimized the sensitivity of the device due to the cervical cancer detection. The DNA nanochip will be more efficient using surface modification of TiO2 nanoparticles with 3-Aminopropyl triethoxysilane (APTES). Furthermore, APTES gain the better functionalization of the adsorption mechanism on IDE. The combination of the DNA probe and the HPV target will produce more sensitivity and speed of the DNA nanochip due to their properties. The IDE has been characterized using current-voltage (IV) measurement. This functionalization of the surface would be applicable, sensitive, selective and low cost for cervical cancer detection.

Concentrations and geographic distribution of selected organic pollutants in Scottish surface soils

International Nuclear Information System (INIS)

Rhind, S.M.; Kyle, C.E.; Kerr, C.; Osprey, M.; Zhang, Z.L.; Duff, E.I.; Lilly, A.; Nolan, A.; Hudson, G.; Towers, W.; Bell, J.; Coull, M.; McKenzie, C.

2013-01-01

Concentrations of selected persistent organic pollutants (POPs) representing three chemical classes (polycyclic aromatic hydrocarbons (PAH), polybrominated diphenyl ethers (PBDE) and polychlorinated biphenyls (PCB) and the organic pollutant diethylhexyl phthalate (DEHP), were determined in surface soil samples (0–5 cm) collected at 20 km grid intersects throughout Scotland over a three-year period. Detectable amounts of all chemical classes and most individual congeners were present in all samples. There were no consistent effects of soil or vegetation type, soil carbon content, pH, altitude or distance from centres of population on concentrations which exhibited extreme variation, even in adjacent samples. It is concluded that soil POPs and DEHP concentrations and associated rates of animal and human exposure were highly variable, influenced by multiple, interacting factors, and not clearly related to local sources but possibly related to wet atmospheric deposition and the organic carbon content of the soil. -- Highlights: •Concentrations of selected organic pollutants in Scottish soils were determined. •Concentrations were highly variable. •There were few effects of soil or vegetation type, soil carbon, pH or altitude. •Distance from cities was not an important determinant of concentrations. •Atmospheric deposition and soil organic carbon content may affect concentrations. -- Soil concentrations of anthropogenic persistent organic pollutants are not clearly related to soil type or pH, vegetation, altitude, or distance from pollutant sources

[Energy dispersive spectrum analysis of surface compositions of selective laser melting cobalt-chromium alloy fabricated by different processing parameters].

Science.gov (United States)

Qian, Liang; Zeng, Li; Wei, Bin; Gong, Yao

2015-06-01

To fabricate selective laser melting cobalt-chromium alloy samples by different processing parameters, and to analyze the changes of energy dispersive spectrum(EDS) on their surface. Nine groups were set up by orthogonal experimental design according to different laser powers,scanning speeds and powder feeding rates(laser power:2500-3000 W, scanning speed: 5-15 mm/s, powder feeding rate: 3-6 r/min). Three cylinder specimens(10 mm in diameter and 3 mm in thickness) were fabricated in each group through Rofin DL 035Q laser cladding system using cobalt-chromium alloy powders which were developed independently by our group.Their surface compositions were then measured by EDS analysis. Results of EDS analysis of the 9 groups fabricated by different processing parameters(Co:62.98%-67.13%,Cr:25.56%-28.50%,Si:0.49%-1.23%) were obtained. They were similar to the compositions of cobalt-chromium alloy used in dental practice. According to EDS results, the surface compositions of the selective laser melting cobalt-chromium alloy samples are stable and controllable, which help us gain a preliminary sight into the range of SLM processing parameters. Supported by "973" Program (2012CB910401) and Research Fund of Science and Technology Committee of Shanghai Municipality (12441903001 and 13140902701).

Synchrotron x-ray diffraction study of liquid surfaces

DEFF Research Database (Denmark)

Als-Nielsen, Jens Aage; Pershan, P.S.

1983-01-01

A spectrometer for X-ray diffraction and refraction studies of horizontal, free surfaces of liquids is described. As an illustration smetic-A layering at the surface of a liquid crystal is presented.......A spectrometer for X-ray diffraction and refraction studies of horizontal, free surfaces of liquids is described. As an illustration smetic-A layering at the surface of a liquid crystal is presented....

First-principles calculation study of mechanism of cation adsorption selectivity of zeolites. A guideline for effective removal of radioactive cesium

International Nuclear Information System (INIS)

Nakamura, Hiroki; Okumura, Masahiko; Machida, Masahiko

2013-01-01

Zeolites have attracted attention in the reprocessing of radioactive nuclear waste because of their high selective affinity for radioisotopes of Cs. Very recently, their useful properties have been widely utilized in decontamination after the accident at the Fukushima Daiichi Nuclear Power Plants. In this study, we study the high selectivity in the Cs adsorption of zeolites using first-principles calculations and clarify the mechanism of the cation selectivity of zeolites. We obtain energy surfaces on all capture locations for Cs/Na ions inside the micropores of a zeolite, 'mordenite', and find three crucial conditions for the highly ion-selective exchange of Na for Cs: 1) micropores with a radius of ∼3 Å, 2) a moderate Al/Si ratio, and 3) a uniform distribution of Al atoms around each micropore. These insights suggest a guideline for developing zeolites with high Cs selectivity and for enhancing the cation selectivity in more general situations. (author)

A new mechanism for selective adsorption of rubber on carbon black surface caused by nano-confinement in SBR/NBR solution

Science.gov (United States)

Kawazoe, Masayuki

A novel mechanism of selective adsorption of rubber molecules onto carbon black surface in a binary immiscible rubber blend solution has been proposed in this dissertation. The phenomenon leads to uneven distribution of carbon black to the specific polymer in the blend and the obtained electrically conductive composite showed drastic reduction of percolation threshold concentration (PTC). The mechanism and the feature of conductive network formation have much potential concerning both fundamental understanding and industrial application to improve conductive polymer composites. In chapter I, carbon black filled conductive polymer composites are briefly reviewed. Then, in chapter II, a mechanism of rubber molecular confinement into carbon black aggregate structure is introduced to explain the selective adsorption of a specific rubber onto carbon black surface in an immiscible rubber solution blend (styrene butadiene rubber (SBR) and acrylonitrile butadiene rubber (NBR) with toluene or chloroform). Next, in chapters III and IV, polymers with various radius of gyration (Rg) and carbon blacks with various aggregate structure are examined to verify the selective adsorption mechanism. Finally, in chapter V, the novel mechanism was applied to create unique meso-/micro-unit conductive network in carbon black dispersed SBR/NBR composites.

The use of in situ Fourier-transform infrared spectroscopy for the study of surface phenomena on electrodes in selected lithium battery electrolyte solutions

Science.gov (United States)

Aurbach, D.; Chusid, O.

This paper presents some examples of surface studies of noble metals and Li electrodes in Li battery electrolyte solutions using in situ FT-IR spectroscopic techniques. These examples include the study of a mixture of solvents, the role of the reduction of salt in the build-up of surface films on the electrodes and the impact of contaminants such as traces of oxgen and water. The techniques included multiple and single internal reflectance modes and external reflectance (SNIFTIRS-type) mode. The following conclusions were drawn from this study: (i) salts containing the -SO 2CF 3 group are much more reactive on Li than LiAsF 6. Their reduction dominates the surface chemistry developed on Li in ethereal solutions; (ii) water reduction on Li in wet 1,3-dioxolane solution may not form stable LiOH films due to the further reaction of the hydroxy group with the solvent; (iii) in spite of its low solubility, oxygen dissolved in propylene carbonate and tetrahydrofuran solutions has some impact on the surface chemistry developed on Li in these solutions (probably due to Li 2O formation).

Tree regeneration following group selection harvesting in southern Indiana

Science.gov (United States)

Dale R. Weigel; George R. Parker

1995-01-01

An increased interest in the use of group selection harvesting in the Central Hardwood forests has emphasized the lack of scientific information about species response under this uneven-aged management system. Tree regeneration response following group selection harvesting was studied on thirty-six group selection openings on the Naval Surface Warfare Center, Crane...

A reconfigurable frequency-selective surface for dual-mode multi-band filtering applications

Science.gov (United States)

Majidzadeh, Maryam; Ghobadi, Changiz; Nourinia, Javad

2017-03-01

A reconfigurable single-layer frequency-selective surface (FSS) with dual-mode multi-band modes of operation is presented. The proposed structure is printed on a compact 10 × 10 mm2 FR4 substrate with the thickness of 1.6 mm. A simple square loop is printed on the front side while another one along with two defected vertical arms is deployed on the backside. To realise the reconfiguration, two pin diodes are embedded on the backside square loop. Suitable insertion of conductive elements along with pin diodes yields in dual-mode multi-band rejection of applicable in service frequency ranges. The first operating mode due to diodes' 'ON' state provides rejection of 2.4 GHz WLAN in 2-3 GHz, 5.2/5.8 GHz WLAN and X band in 5-12 GHz, and a part of Ku band in 13.9-16 GHz. In diodes 'OFF' state, the FSS blocks WLAN in 4-7.3 GHz, X band in 8-12.7 GHz as well as part of Ku band in 13.7-16.7 GHz. As well, high attenuation of incident waves is observed by a high shielding effectiveness (SE) in the blocked frequency bands. Also, a stable behaviour against different polarisations and angles of incidence is obtained. Comprehensive studies are conducted on a fabricated prototype to assess its performance from which encouraging results are obtained.

Triassico: A Sphere Positioning System for Surface Studies with IBA Techniques

Science.gov (United States)

Fontana, Cristiano L.; Doyle, Barney L.

We propose here a novel device, called the Triassico, to microscopically study the entire surface of millimeter-sized spheres. The sphere dimensions can be as small as 1 mm, and the upper limit defined only by the power and by the mechanical characteristics of the motors used. Three motorized driving rods are arranged so an equilateral triangle is formed by the rod's axes, on such a triangle the sphere sits. Movement is achieved by rotating the rods with precise relative speeds and by exploiting the friction between the sphere and the rods surfaces. The sphere can be held in place by gravity or by an opposing trio of rods. By rotating the rods with specific relative angular velocities, a net torque can be exerted on the sphere which then rotates. No repositioning of the sphere or of the motors is needed to cover the full surface with the investigating tools. An algorithm was developed to position the sphere at any arbitrary polar and azimuthal angle. The algorithm minimizes the number of rotations needed by the rods, in order to efficiently select a particular position on the sphere surface. A prototype Triassico was developed for the National Ignition Facility, of the Lawrence Livermore National Laboratory (Livermore, California, USA), as a sphere manipulation apparatus for ion microbeam analysis at Sandia National Laboratories (Albuquerque, NM, USA) of Xe-doped DT inertial confinement fusion fuel spheres. Other applications span from samples orientation, ball bearing manufacturing, or jewelry.

A Comparison Between Jerusalem Cross and Square Patch Frequency Selective Surfaces for Low Profile Antenna Applications

Science.gov (United States)

Cure, David; Weller, Thomas; Miranda, Felix A.

2011-01-01

In this paper, a comparison between Jerusalem Cross (JC) and Square Patch (SP) based Frequency Selected Surfaces (FSS) for low profile antenna applications is presented. The comparison is aimed at understanding the performance of low profile antennas backed by high impedance surfaces. In particular, an end loaded planar open sleeve dipole (ELPOSD) antenna is examined due to the various parameters within its configuration, offering significant design flexibility and a wide operating bandwidth. Measured data of the antennas demonstrate that increasing the number of unit cells improves the fractional bandwidth. The antenna bandwidth increased from 0.8% to 1.8% and from 0.8% to 2.7% for the JC and SP structures, respectively. The number of unit cells was increased from 48 to 80 for the JC-FSS and from 24 to 48 for the SP-FSS.

Variations in uranium and radioactivity levels in surface and ground water at selected sites in British Columbia, April 1980 - March 1981

International Nuclear Information System (INIS)

1981-07-01

This report summarizes field and analytical work carried out between April, 1980 and March, 1981 on a program to investigate uranium and radioactivity levels in potable surface and ground water in selected regions throughout British Columbia

Surface study of fusion research in universities linkage organization

International Nuclear Information System (INIS)

Miyahara, Akira.

1980-04-01

The surface studies for nuclear fusion research consist of the studies on the surface process and the surface damage. The problems with the surface study are different at different research stages. The plasma-wall interaction in the ignition stage is mainly concerned with heating. The impurity control becomes important in the breakeven stage. In the longer burn experiment, the problems of plasma contamination and ash accumulation are serious, and the blistering is also a problem. From the reactor aspect, the reduction of life of wall due to the irradiation of high fluence must be considered. The surface damage due to plasma disruption is a very big problem. The activities concerning the surface studies in university-linked organizations are the surface characterization for fusion reactor materials by low energy ion scattering spectroscopy, the high power ion irradiation test for CTR first wall, data compilation on plasma-wall interaction, the studies of sputtering process and surface coating, and the study on hydrogen isotope permeation through metals for fusion reactors. Other activities such as the sample characterization at many universities using the SUS 304 samples from the same lot, and the collaboration works on JIPP-T-2 plasma wall experiments are introduced. Concerning the surface study, US-Japan or international collaboration are strongly expected. (Kato, T.)

Selected Trace Element Concentrations in Peat Used for Cosmetic Production – A Case Study from Southern Poland

Directory of Open Access Journals (Sweden)

Glina Bartłomiej

2016-12-01

Full Text Available The aim of the study was to assess the concentration of selected trace elements in organic soils used as a source to obtain a unique peat extract for cosmetics production. Peat material for laboratory analysis were collected from fen peatland located in the Prosna River Valley (Borek village. Studied peatland is managed by “Torf Corporation” company as a source of material to obtain peat extract for cosmetics production. In the collected soil samples (four soil profiles Zn, Cu and Pb concentrations were determined by using atomic absorption spectrometer SpectraAA 220 (Varian, after acid digestion. Obtained results showed that the highest concentrations of selected trace elements were recorded in the surface horizons of organic soils. This fact might be the results of Prosna river flooding or air deposition. Howevere, according to the new Polish regulations (Ordinance of the Minister for Environment 01.09.2016 - the way of conducting contamination assessment of the earth surface, the content of trace elements in the examined soils was greatly belowe the permissible limit for areas from group IV (mine lands. Thus, described soils are proper to obtain peat extract used as a component in cosmetic production.

Theoretical study of chlordecone and surface groups interaction in an activated carbon model under acidic and neutral conditions.

Science.gov (United States)

Gamboa-Carballo, Juan José; Melchor-Rodríguez, Kenia; Hernández-Valdés, Daniel; Enriquez-Victorero, Carlos; Montero-Alejo, Ana Lilian; Gaspard, Sarra; Jáuregui-Haza, Ulises Javier

2016-04-01

Activated carbons (ACs) are widely used in the purification of drinking water without almost any knowledge about the adsorption mechanisms of the persistent organic pollutants. Chlordecone (CLD, Kepone) is an organochlorinated synthetic compound that has been used mainly as agricultural insecticide. CLD has been identified and listed as a persistent organic pollutant by the Stockholm Convention. The selection of the best suited AC for this type of contaminants is mainly an empirical and costly process. A theoretical study of the influence of AC surface groups (SGs) on CLD adsorption is done in order to help understanding the process. This may provide a first selection criteria for the preparation of AC with suitable surface properties. A model of AC consisting of a seven membered ring graphene sheet (coronene) with a functional group on the edge was used to evaluate the influence of the SGs over the adsorption. Multiple Minima Hypersurface methodology (MMH) coupled with PM7 semiempirical Hamiltonian was employed in order to study the interactions of the chlordecone with SGs (hydroxyl and carboxyl) at acidic and neutral pH and different hydration conditions. Selected structures were re-optimized using CAM-B3LYP to achieve a well-defined electron density to characterize the interactions by the Quantum Theory of Atoms in Molecules approach. The deprotonated form of surface carboxyl and hydroxyl groups of AC models show the strongest interactions, suggesting a chemical adsorption. An increase in carboxylic SGs content is proposed to enhance CLD adsorption onto AC at neutral pH conditions. Copyright © 2016 Elsevier Inc. All rights reserved.

Surface studies of plasma processed Nb samples

International Nuclear Information System (INIS)

Tyagi, Puneet V.; Doleans, Marc; Hannah, Brian S.; Afanador, Ralph; Stewart, Stephen; Mammosser, John; Howell, Matthew P; Saunders, Jeffrey W; Degraff, Brian D; Kim, Sang-Ho

2015-01-01

Contaminants present at top surface of superconducting radio frequency (SRF) cavities can act as field emitters and restrict the cavity accelerating gradient. A room temperature in-situ plasma processing technology for SRF cavities aiming to clean hydrocarbons from inner surface of cavities has been recently developed at the Spallation Neutron Source (SNS). Surface studies of the plasma-processed Nb samples by Secondary ion mass spectrometry (SIMS) and Scanning Kelvin Probe (SKP) showed that the NeO_2 plasma processing is very effective to remove carbonaceous contaminants from top surface and improves the surface work function by 0.5 to 1.0 eV.

Copper surfaces are associated with significantly lower concentrations of bacteria on selected surfaces within a pediatric intensive care unit.

Science.gov (United States)

Schmidt, Michael G; von Dessauer, Bettina; Benavente, Carmen; Benadof, Dona; Cifuentes, Paulina; Elgueta, Alicia; Duran, Claudia; Navarrete, Maria S

2016-02-01

Health care-associated infections result in significant patient morbidity and mortality. Although cleaning can remove pathogens present on hospital surfaces, those surfaces may be inadequately cleaned or recontaminated within minutes. Because of copper's inherent and continuous antimicrobial properties, copper surfaces offer a solution to complement cleaning. The objective of this study was to quantitatively assess the bacterial microbial burden coincident with an assessment of the ability of antimicrobial copper to limit the microbial burden associated with 3 surfaces in a pediatric intensive care unit. A pragmatic trial was conducted enrolling 1,012 patients from 2 high acuity care units within a 249-bed tertiary care pediatric hospital over 12 months. The microbial burden was determined from 3 frequently encountered surfaces, regardless of room occupancy, twice monthly, from 16 rooms, 8 outfitted normally and 8 outfitted with antimicrobial copper. Copper surfaces were found to be equivalently antimicrobial in pediatric settings to activities reported for adult medical intensive care units. The log10 reduction to the microbial burden from antimicrobial copper surfaced bed rails was 1.996 (99%). Surprisingly, introduction of copper objects to 8 study rooms was found to suppress the microbial burden recovered from objects assessed in control rooms by log10 of 1.863 (73%). Copper surfaces warrant serious consideration when contemplating the introduction of no-touch disinfection technologies for reducing burden to limit acquisition of HAIs. Copyright © 2016 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.

Surface excitation correction of electron IMFP of selected polymers

International Nuclear Information System (INIS)

Gergely, G.; Orosz, G.T.; Lesiak, B.; Jablonski, A.; Toth, J.; Varga, D.

2004-01-01

Complete text of publication follows. The IMFP [1] of selected polymers: polythiophenes, polyanilines, polyethylene (PE) [2] was determined by EPES [3] experiments, using Si, Ge and Ag (for PE) reference samples. Experiments were evaluated by Monte Carlo (MC) simulations [1] applying the NIST 64 (1996 and 2002) databases and IMFP data of Tanuma and Gries [1]. The integrated experimental elastic peak ratios of sample and reference are different from those calculated by Monte Carlo (MC) simulation [1]. The difference was attributed to the difference of surface excitation parameters (SEP) [4] of the sample and reference. The SEP parameters of the reference samples were taken from Chen and Werner. A new procedure was developed for experimental determination of the SEP parameters of polymer samples. It is a trial and error method for optimising the SEP correction of the IMFP and the correction of experimental elastic peak ratio [4]. Experiments made with a HSA spectrometer [5] covered the E = 0.2-2 keV energy range. The improvements with SEP correction appears in reduc- ing the difference between the corrected and MC calculated IMFPs, assuming Gries and Tanuma's et al IMFPs [1] for polymers and standard respectively. The experimental peak areas were corrected for the hydrogen peak. For the direct detection of hydrogen see Ref. [6] and [7]. Results obtained with the different NIST 64 databases and atomic potentials [8] are presented. This work was supported by the Hungarian Science Foundation of OTKA: T037709 and T038016. (author)

Structural analysis under the Blanket Comparison and Selection Study

International Nuclear Information System (INIS)

Majumdar, S.

1985-01-01

Structural design procedures followed in the Blanket Comparison and Selection Study are briefly reviewed. The American Society of Mechanical Engineers Boilers and Pressure Vessels Code, Section III, Code Case N47 has been used as a design guide. Its relevance to fusion reactor applications, however, is open to question and needs to be evaluated in the future. The primary structural problem encountered in tokamak blanket designs is the high thermal stress due to surface heat flux, with fatigue being an additional concern for pulsed systems. The conflicting requirements of long erosion life and high surface heat flux capability imply that some form of stress relief in the first-wall region will be necessary. Simplified stress and fatigue crack growth analyses are presented to show that the use of orthogonally grooved first wall may be a potential solution for mitigating the thermal stress problem. A comparison of three structural alloys on the basis of both grooved and nongrooved first-wall designs is also presented. Other structural problems encountered in tokamak designs include stresses due to plasma disruptions, and magnetohydrodynamic (MHD) pressure drop in liquid-metal-cooled systems. In particular, it is shown that the maximum stress in the side wall of a uniform duct generated by MHD pressure drop cannot be reduced by increasing the wall thickness or by decreasing the span. In contract to tokamak blankets, tandem mirror blankets are far less severely stressed because of a much lower surface heat flux, coolant pressure, and also because of their axisymmetric geometry. Both blankets, however, will require detailed structural dynamics analysis to verify their ability to withstand seismic loadings if the heavy 17Li-83Pb is used as a coolant

Trends in Surface-Water Quality at Selected Ambient-Monitoring Network Stations in Kentucky, 1979-2004

Science.gov (United States)

Crain, Angela S.; Martin, Gary R.

2009-01-01

Increasingly complex water-management decisions require water-quality monitoring programs that provide data for multiple purposes, including trend analyses, to detect improvement or deterioration in water quality with time. Understanding surface-water-quality trends assists resource managers in identifying emerging water-quality concerns, planning remediation efforts, and evaluating the effectiveness of the remediation. This report presents the results of a study conducted by the U.S. Geological Survey, in cooperation with the Kentucky Energy and Environment Cabinet-Kentucky Division of Water, to analyze and summarize long-term water-quality trends of selected properties and water-quality constituents in selected streams in Kentucky's ambient stream water-quality monitoring network. Trends in surface-water quality for 15 properties and water-quality constituents were analyzed at 37 stations with drainage basins ranging in size from 62 to 6,431 square miles. Analyses of selected physical properties (temperature, specific conductance, pH, dissolved oxygen, hardness, and suspended solids), for major ions (chloride and sulfate), for selected metals (iron and manganese), for nutrients (total phosphorus, total nitrogen, total Kjeldahl nitrogen, nitrite plus nitrate), and for fecal coliform were compiled from the Commonwealth's ambient water-quality monitoring network. Trend analyses were completed using the S-Plus statistical software program S-Estimate Trend (S-ESTREND), which detects trends in water-quality data. The trend-detection techniques supplied by this software include the Seasonal Kendall nonparametric methods for use with uncensored data or data censored with only one reporting limit and the Tobit-regression parametric method for use with data censored with multiple reporting limits. One of these tests was selected for each property and water-quality constituent and applied to all station records so that results of the trend procedure could be compared among

Selective detection of Fe and Mn species at mineral surfaces in weathered granite by conversion electron yield X-ray absorption fine structure

International Nuclear Information System (INIS)

Itai, Takaaki; Takahashi, Yoshio; Uruga, Tomoya; Tanida, Hajime; Iida, Atsuo

2008-01-01

A new method for the speciation of Fe and Mn at mineral surfaces is proposed using X-ray absorption fine structure in conversion electron yield mode (CEY-XAFS). This method generally reflects information on the species at the sub-μm scale from the particle surface due to the limited escape depth of the inelastic Auger electron. The surface sensitivity of this method was assessed by experiments on two samples of granite showing different degrees of weathering. The XANES spectra of the Fe-K and Mn-K edge clearly gave different information for CEY and fluorescence (FL) modes. These XANES spectra of Fe and Mn show a good fit upon application of least-squares fitting using ferrihydrite/MnO 2 and biotite as the end members. The XANES spectra collected by CEY mode provided more selective information on the secondary phases which are probably present at the mineral surfaces. In particular, CEY-XANES spectra of Mn indicated the presence of Mn oxide in unweathered granite despite a very small contribution of Mn oxide being indicated by FL-XANES and selective chemical-extraction analyses. Manganese oxide could not be detected by micro-beam XANES (beam size: 5 x 5 μm 2 ) in unweathered granite, suggesting that Mn oxide thinly and ubiquitously coats mineral surface at a sub-μm scale. This information is important, since Mn oxide can be the host for various trace elements. CEY-XAFS can prove to be a powerful tool as a highly sensitive surface speciation method. Combination of CEY and FL-XAFS will help identify minor phases that form at mineral surfaces, but identification of Fe and Mn oxides at mineral surfaces is critical to understand the migration of trace elements in water-rock interaction

Selective detection of Fe and Mn species at mineral surfaces in weathered granite by conversion electron yield X-ray absorption fine structure

Energy Technology Data Exchange (ETDEWEB)

Itai, Takaaki [Department of Earth and Planetary Systems Science, Hiroshima University, Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526 (Japan)], E-mail: itai-epss@hiroshima-u.ac.jp; Takahashi, Yoshio [Department of Earth and Planetary Systems Science, Hiroshima University, Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526 (Japan); Uruga, Tomoya; Tanida, Hajime [Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); Iida, Atsuo [Photon Factory, National Laboratory for High Energy Physics, O-ho, Tsukuba, Ibaraki 305 (Japan)

2008-09-15

A new method for the speciation of Fe and Mn at mineral surfaces is proposed using X-ray absorption fine structure in conversion electron yield mode (CEY-XAFS). This method generally reflects information on the species at the sub-{mu}m scale from the particle surface due to the limited escape depth of the inelastic Auger electron. The surface sensitivity of this method was assessed by experiments on two samples of granite showing different degrees of weathering. The XANES spectra of the Fe-K and Mn-K edge clearly gave different information for CEY and fluorescence (FL) modes. These XANES spectra of Fe and Mn show a good fit upon application of least-squares fitting using ferrihydrite/MnO{sub 2} and biotite as the end members. The XANES spectra collected by CEY mode provided more selective information on the secondary phases which are probably present at the mineral surfaces. In particular, CEY-XANES spectra of Mn indicated the presence of Mn oxide in unweathered granite despite a very small contribution of Mn oxide being indicated by FL-XANES and selective chemical-extraction analyses. Manganese oxide could not be detected by micro-beam XANES (beam size: 5 x 5 {mu}m{sup 2}) in unweathered granite, suggesting that Mn oxide thinly and ubiquitously coats mineral surface at a sub-{mu}m scale. This information is important, since Mn oxide can be the host for various trace elements. CEY-XAFS can prove to be a powerful tool as a highly sensitive surface speciation method. Combination of CEY and FL-XAFS will help identify minor phases that form at mineral surfaces, but identification of Fe and Mn oxides at mineral surfaces is critical to understand the migration of trace elements in water-rock interaction.

Horseradish peroxidase immobilized on copper surfaces and applications in selective electrocatalysis of p-dihydroxybenzene

Energy Technology Data Exchange (ETDEWEB)

Wang, Chuntao, E-mail: tsyj1992@126.com [Department of Chemistry, Taiyuan Normal University, Taiyuan 030031 (China); Institute of Energy and Environmental Electrochemistry, Taiyuan Normal University, Taiyuan 030031 (China); Luo, Xiaoxiao [Department of Natural Science, Michigan State University, MI 48823,USA (United States); Jia, Zehui [Department of Chemistry, Taiyuan Normal University, Taiyuan 030031 (China); Institute of Energy and Environmental Electrochemistry, Taiyuan Normal University, Taiyuan 030031 (China); Shi, Qinghua; Zhu, Ritao [Department of Chemistry, Taiyuan Normal University, Taiyuan 030031 (China)

2017-06-01

Abstract: Horseradish Peroxidase (HRP) was immobilized on copper surfaces with the linker of L-Cysteine (L-Cys) self-assembled films to form Cu/L-Cys/HRP electrodes. The activity of HRP can be preserved by the Cu/L-Cys self-assembled films. The Cu/L-Cys/HRP electrodes can be used for the selective electrocatalytic oxidase of p-dihydroxybenzen in absent of H{sub 2}O{sub 2}. The optimum pH for electrocatalyzing p-dihydroxybenzen was 5.5 or 7.0, which corresponds to the isoelectric points of L-Cys and HRP, respectively. X-ray photoelectron spectroscopy (XPS) provided the evidence that L-Cys linked with Cu surface by the Cu− S bond. Fourier transform infrared spectroscopy (FTIR) analyses indicated that aromatic plane of p-dihydroxybenzen was connected parallel to porphyrin ring of heme in HRP. Quantum chemical calculation of density functional theory (DFT) revealed that symmetry of molecular structure and minimum space steric hindrance for p-dihydroxybenzen were benefit to combination with HRP. Moreover, the lowest energy of LUMO and most negative charges of oxygen atom on hydroxyl group of p-dihydroxybenzen were advantage to lose the hydrogen atom of hydroxyl group to be oxided.

A recyclable Au(I) catalyst for selective homocoupling of arylboronic acids: significant enhancement of nano-surface binding for stability and catalytic activity.

Science.gov (United States)

Zhang, Xin; Zhao, Haitao; Wang, Jianhui

2010-08-01

Au nanoparticles stabilized by polystyrene-co-polymethacrylic acid microspheres (PS-co-PMAA) were prepared and characterized via X-ray diffraction (XRD), and transmission electron microscope (TEM). The Au nanoparticles supported on the microspheres showed highly selective catalytic activity for homo-coupling reactions of arylboronic acids in a system of aryl-halides and arylboronic acids. X-ray photoelectron spectroscopy (XPS) spectra of the catalyst shows large amounts of Au(I) complexes band to the surface of the Au nanoparticles, which contributes to the selective homocoupling of the arylboronic acids. More importantly, this supported Au complex is a highly recyclable catalyst. The supported Au catalyst can be recycled and reused at least 6 times for a phenylboronic acid reactant, whereas the parent complex shows very low catalytic activity for this compound. The high catalytic activity of this material is attributed to: (1) the high surface to volume ratio which leads to more active sites being exposed to reactants; (2) the strong surface binding of the Au nanoparticle to the Au(I) complexes, which enhances both the stability and the catalytic activity of these complexes.

Macromorphological and micromorphological studies of four selected passiflora species in peninsular malaysia

International Nuclear Information System (INIS)

Veeramohan, R.; Haron, N.W.

2015-01-01

Taxonomic studies of four selected Passiflora species; Passiflora edulis Sims (Passion fruit), Passiflora coccinea Aubl. (Scarlet passion flower), Passiflora foetida L. (Stinking passion flower) and Passiflora incarnata L. (Fragrant passion flower) were carried out to distinguish their morphological characteristics. Macromorphological characters on the leaves, flowers and fruits of all four Passiflora species were observed under a binocular microscope and they varied characteristically in terms of colour, texture and shape of flowers, leaves and fruits. Jeol JSM-7500F Scanning Electron Microscope was used to observe the micromorphological characters such as stomata, trichomes, and leaf surface indumentum of each Passiflora species. Micromorphologically, each species varied in types and sizes of stomata, epidermal. (author)

Particle compositions with a pre-selected cell internalization mode

Science.gov (United States)

Decuzzi, Paolo (Inventor); Ferrari, Mauro (Inventor)

2012-01-01

A method of formulating a particle composition having a pre-selected cell internalization mode involves selecting a target cell having surface receptors and obtaining particles that have i) surface moieties, that have an affinity for or are capable of binding to the surface receptors of the cell and ii) a preselected shape, where a surface distribution of the surface moieties on the particles and the shape of the particles are effective for the pre-selected cell internalization mode.

Microstructural and surface modifications and hydroxyapatite coating of Ti-6Al-4V triply periodic minimal surface lattices fabricated by selective laser melting.

Science.gov (United States)

Yan, Chunze; Hao, Liang; Hussein, Ahmed; Wei, Qingsong; Shi, Yusheng

2017-06-01

Ti-6Al-4V Gyroid triply periodic minimal surface (TPMS) lattices were manufactured by selective laser melting (SLM). The as-built Ti-6Al-4V lattices exhibit an out-of-equilibrium microstructure with very fine α' martensitic laths. When subjected to the heat treatment of 1050°C for 4h followed by furnace cooling, the lattices show a homogenous and equilibrium lamellar α+β microstructure with less dislocation and crystallographic defects compared with the as-built α' martensite. The as-built lattices present very rough strut surfaces bonded with plenty of partially melted metal particles. The sand blasting nearly removed all the bonded metal particles, but created many tiny cracks. The HCl etching eliminated these tiny cracks, and subsequent NaOH etching resulted in many small and shallow micro-pits and develops a sodium titanate hydrogel layer on the surfaces of the lattices. When soaked in simulated body fluid (SBF), the Ti-6Al-4V TPMS lattices were covered with a compact and homogeneous biomimetic hydroxyapatite (HA) layer. This work proposes a new method for making Ti-6Al-4V TPMS lattices with a homogenous and equilibrium microstructure and biomimetic HA coating, which show both tough and bioactive characteristics and can be promising materials usable as bone substitutes. Copyright © 2017 Elsevier B.V. All rights reserved.

Plasma surface interaction studies in Japan

International Nuclear Information System (INIS)

Hino, T.; Hirohata, Y.; Yamashina, T.

1994-01-01

In order to achieve a long burning time period in a fusion reactor, the interactions between the plasma facing materials and the fusion plasma have to be well controlled. Namely, the radiation loss due to impurities and deterioration of the energy confinement time due to fuel particle recyclings have to be suppressed, in addition to the requirement of heat removal based on a high heat flux component. Recently, in Japan, the plasma facing material/component has been very actively developed for ITER and Large Helical Device (LHD). In this review paper, we briefly introduce the following issues, (1) progress of plasma surface interactions in tokamaks and helical devices, (2) development of plasma facing materials, (3) divertor development, (4) boronization, (5) selective pumping of helium ash, (6) tritium retention, and (7) neutron damage of graphite plasma facing material. (author)

Laser Induced Selective Activation For Subsequent Autocatalytic Electroless Plating

DEFF Research Database (Denmark)

Zhang, Yang

. The third hypothesis is that the activation and rinsing process can be described by diffusion. This hypothesis is proved using Fick’s diffusion laws combined with the short-time-plating experiment. The influence of laser parameters on the surface structure is investigated for Nd:YAG, UV, and fiber lasers......The subject of this PhD thesis is “Laser induced selective activation for subsequent autocatalytic electroless plating.” The objective of the project is to investigate the process chains for micro structuring of polymer surfaces for selective micro metallization. Laser induced selective activation...... (LISA) is introduced and studied as a new technique for producing 3D moulded interconnect devices (3D-MIDs). This technique enables the metallization of polymer surface modified by laser and subsequently activated by a PdCl2/SnCl2 system. Various technologies exist on an industrial level...

Ni-Doping Effects on Oxygen Removal from an Orthorhombic Mo ₂ C (001) Surface: A Density Functional Theory Study

Energy Technology Data Exchange (ETDEWEB)

Zhou, Mingxia [Department; Cheng, Lei [Materials; Choi, Jae-Soon [Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN 37831, Unites States; Liu, Bin [Department; Curtiss, Larry A. [Materials; Assary, Rajeev S. [Materials

2018-01-11

Density functional theory (DFT) calculations were used to investigate the effect of Ni dopants on the removal of chemisorbed oxygen (O*) from the Mo-terminated (T-Mo) and C-terminated (Tc) Mo2C(001) surfaces. The removal of adsorbed oxygen from the catalytic site is essential to maintain the long-term activity and selectivity of the carbide catalysts in the deoxygenation process related to bio-oil stabilization and upgrading. In this contribution, the computed reaction energetics and reaction barriers of O* removal were compared among undoped and Ni-doped Mo2C(001) surfaces. The DFT calculations indicate that selected Ni-doped surfaces such as Ni adsorbed on T-Mo and Tc Mo2C(001) surfaces enable weaker binding of important reactive intermediates (O*, OH*) compared to the undoped counterparts, which is beneficial for the O* removal from the catalyst surface. This study thus confirms the promoting effect of the Ni dopant on O* removal reaction on the T-Mo Mo2C(001) and Tc Mo2C(001) surfaces. This computational prediction has been confirmed by the temperature-programmed reduction profiles of Mo2C and Ni-doped Mo2C catalysts, which had been passivated and stored in an oxygen environment.

Bone ingrowth potential of electron beam and selective laser melting produced trabecular-like implant surfaces with and without a biomimetic coating

NARCIS (Netherlands)

Biemond, J.E.; Hannink, G.; Verdonschot, Nicolaas Jacobus Joseph; Buma, P.

2013-01-01

The bone ingrowth potential of trabecular-like implant surfaces produced by either selective laser melting (SLM) or electron beam melting (EBM), with or without a biomimetic calciumphosphate coating, was examined in goats. For histological analysis and histomorphometry of bone ingrowth depth and

Inspection of freeform surfaces considering uncertainties in measurement, localization and surface reconstruction

International Nuclear Information System (INIS)

Mehrad, Vahid; Xue, Deyi; Gu, Peihua

2013-01-01

Inspection of a manufactured freeform surface can be conducted by building its surface model and comparing this manufactured surface model with the ideal design surface model and its tolerance requirement. The manufactured freeform surface model is usually achieved by obtaining measurement points on the manufactured surface, transforming these measurement points from the measurement coordinate system to the design coordinate system through localization, and reconstructing the surface model using the localized measurement points. In this research, a method was developed to estimate the locations and their variances of any selected points on the reconstructed freeform surface considering different sources of uncertainties in measurement, localization and surface reconstruction processes. In this method, first locations and variances of the localized measurement points are calculated considering uncertainties of the measurement points and uncertainties introduced in the localization processes. Then locations and variances of points on the reconstructed freeform surface are obtained considering uncertainties of the localized measurement points and uncertainties introduced in the freeform surface reconstruction process. Two case studies were developed to demonstrate how these three different uncertainty sources influence the quality of the reconstructed freeform curve and freeform surface in inspection. (paper)

STUDIES ON THE SELECTED PROPERTIES OF C45 STEEL ELEMENTS SURFACE LAYER AFTER LASER CUTTING, FINISHING MILLING AND BURNISHING

Directory of Open Access Journals (Sweden)

Agnieszka Skoczylas

2016-12-01

microhardness of C45 steel elements after laser cutting, and then finishing milling or burnishing. The aim of milling was to get rid of the characteristic “striae” after laser cutting and to improve geometric accuracy. Burnishing caused hardening of C45 steel elements’ surface layer after laser cutting and improvement in surface roughness. In order to measure surface roughness, the Hommel – Etamic device T8000 RC120 – 400 with software was used. The roughness parameters that were analyzed in the article were: amplitude parameters, height parameters and Abbott - Firestone curve. The microhardness measurements were made with the use of Vicker’s hardness test with a weight of 50 g. As a result of the finishing of the surface after cutting, a decrease in surface roughness and improvements in functional qualities were noticed. In addition, hardening of the edgeside area also occurred, which is an advantageous phenomenon.

Hybrid selective surface hydrophilization and froth flotation separation of hazardous chlorinated plastics from E-waste with novel nanoscale metallic calcium composite

Energy Technology Data Exchange (ETDEWEB)

Mallampati, Srinivasa Reddy, E-mail: srireddys@ulsan.ac.kr; Heo, Je Haeng; Park, Min Hee

2016-04-05

Highlights: • Nanometallic Ca/CaO treatment significantly enhanced PVC surface hydrophilicity. • The contact angle of PVC significantly decreased compared to other E-waste plastics. • 100% of PVC was selectively separated with 96.4% purity from E-waste plastics. • SEM/XPS results indicated an oxidative degradation of chlorides on the PVC surface. • Hybrid treatment with nanometallic Ca/CaO and froth flotation is effective. - Abstract: Treatment by a nanometallic Ca/CaO composite has been found to selectively hydrophilize the surface of polyvinyl chloride (PVC), enhancing its wettability and thereby promoting its separation from E-waste plastics by means of froth flotation. The treatment considerably decreased the water contact angle of PVC, by about 18°. The SEM images of the PVC plastic after treatment displayed significant changes in their surface morphology compared to other plastics. The SEM-EDS results reveal that a markedly decrease of [Cl] concentration simultaneously with dramatic increase of [O] on the surface of the PCV samples. XPS results further confirmed an increase of hydrophilic functional groups on the PVC surface. Froth flotation at 100 rpm mixing speed was found to be optimal, separating 100% of the PVC into a settled fraction of 96.4% purity even when the plastics fed into the reactor were of nonuniform size and shape. The total recovery of PVC-free plastics in E-waste reached nearly 100% in the floated fraction, significantly improved from the 20.5 wt% of light plastics that can be recovered by means of conventional wet gravity separation. The hybrid method of nanometallic Ca/CaO treatment and froth flotation is effective in the separation of hazardous chlorinated plastics from E-waste plastics.

Hybrid selective surface hydrophilization and froth flotation separation of hazardous chlorinated plastics from E-waste with novel nanoscale metallic calcium composite

International Nuclear Information System (INIS)

Mallampati, Srinivasa Reddy; Heo, Je Haeng; Park, Min Hee

2016-01-01

Highlights: • Nanometallic Ca/CaO treatment significantly enhanced PVC surface hydrophilicity. • The contact angle of PVC significantly decreased compared to other E-waste plastics. • 100% of PVC was selectively separated with 96.4% purity from E-waste plastics. • SEM/XPS results indicated an oxidative degradation of chlorides on the PVC surface. • Hybrid treatment with nanometallic Ca/CaO and froth flotation is effective. - Abstract: Treatment by a nanometallic Ca/CaO composite has been found to selectively hydrophilize the surface of polyvinyl chloride (PVC), enhancing its wettability and thereby promoting its separation from E-waste plastics by means of froth flotation. The treatment considerably decreased the water contact angle of PVC, by about 18°. The SEM images of the PVC plastic after treatment displayed significant changes in their surface morphology compared to other plastics. The SEM-EDS results reveal that a markedly decrease of [Cl] concentration simultaneously with dramatic increase of [O] on the surface of the PCV samples. XPS results further confirmed an increase of hydrophilic functional groups on the PVC surface. Froth flotation at 100 rpm mixing speed was found to be optimal, separating 100% of the PVC into a settled fraction of 96.4% purity even when the plastics fed into the reactor were of nonuniform size and shape. The total recovery of PVC-free plastics in E-waste reached nearly 100% in the floated fraction, significantly improved from the 20.5 wt% of light plastics that can be recovered by means of conventional wet gravity separation. The hybrid method of nanometallic Ca/CaO treatment and froth flotation is effective in the separation of hazardous chlorinated plastics from E-waste plastics.

Studies on the matched potential method for determining the selectivity coefficients of ion-selective electrodes based on neutral ionophores: experimental and theoretical verification.

Science.gov (United States)

Tohda, K; Dragoe, D; Shibata, M; Umezawa, Y

2001-06-01

A theory is presented that describes the matched potential method (MPM) for the determination of the potentiometric selectivity coefficients (KA,Bpot) of ion-selective electrodes for two ions with any charge. This MPM theory is based on electrical diffuse layers on both the membrane and the aqueous side of the interface, and is therefore independent of the Nicolsky-Eisenman equation. Instead, the Poisson equation is used and a Boltzmann distribution is assumed with respect to all charged species, including primary, interfering and background electrolyte ions located at the diffuse double layers. In this model, the MPM-selectivity coefficients of ions with equal charge (ZA = ZB) are expressed as the ratio of the concentrations of the primary and interfering ions in aqueous solutions at which the same amounts of the primary and interfering ions permselectively extracted into the membrane surface. For ions with unequal charge (ZA not equal to ZB), the selectivity coefficients are expressed as a function not only of the amounts of the primary and interfering ions permeated into the membrane surface, but also of the primary ion concentration in the initial reference solution and the delta EMF value. Using the measured complexation stability constants and single ion distribution coefficients for the relevant systems, the corresponding MPM selectivity coefficients can be calculated from the developed MPM theory. It was found that this MPM theory is capable of accurately and precisely predicting the MPM selectivity coefficients for a series of ion-selective electrodes (ISEs) with representative ionophore systems, which are generally in complete agreement with independently determined MPM selectivity values from the potentiometric measurements. These results also conclude that the assumption for the Boltzmann distribution was in fact valid in the theory. The recent critical papers on MPM have pointed out that because the MPM selectivity coefficients are highly concentration

Fabrication of a bionic microstructure on a C/SiC brake lining surface: Positive applications of surface defects for surface wetting control

Science.gov (United States)

Wu, M. L.; Ren, C. Z.; Xu, H. Z.; Zhou, C. L.

2018-05-01

The material removal processes generate interesting surface topographies, unfortunately, that was usually considered to be surface defects. To date, little attention has been devoted to the positive applications of these interesting surface defects resulted from laser ablation to improve C/SiC surface wettability. In this study, the formation mechanism behind surface defects (residual particles) is discussed first. The results showed that the residual particles with various diameters experienced regeneration and migration, causing them to accumulate repeatedly. The effective accumulation of these residual particles with various diameters provides a new method about fabricating bionic microstructures for surface wetting control. The negligible influence of ablation processes on the chemical component of the subsurface was studied by comparing the C-O-Si weight percentage at the C/SiC subsurface. A group of microstructures were fabricated under different laser trace and different laser parameters. Surface wettability experimental results for different types of microstructures were compared. The results showed that the surface wettability increased as the laser scanning speed decreased. The surface wettability increased with the density of the laser scanning trace. We also demonstrated the application of optimized combination of laser parameters and laser trace to simulate a lotus leaf's microstructure on C/SiC surfaces. The parameter selection depends on the specific material properties.

Surface study of liquid 3He using surface state electrons

International Nuclear Information System (INIS)

Shirahama, K.; Ito, S.; Suto, H.; Kono, K.

1995-01-01

We have measured the mobility of surface state electrons (SSE) on liquid 3 He, μ 3 , aiming to study the elementary surface excitations of the Fermi liquid. A gradual increase of μ 3 below 300 mK is attributed to the scattering of electrons by ripplons. Ripplons do exist in 3 He down to 100 mK. We observe an abrupt decrease of μ 3 , due to the transition to the Wigner solid (WS). The dependences of the WS conductivity and mobility on temperature and magnetic field differ from the SSE behavior on liquid 4 He

Investigation on Selective Laser Melting AlSi10Mg Cellular Lattice Strut: Molten Pool Morphology, Surface Roughness and Dimensional Accuracy

Directory of Open Access Journals (Sweden)

Xuesong Han

2018-03-01

Full Text Available AlSi10Mg inclined struts with angle of 45° were fabricated by selective laser melting (SLM using different scanning speed and hatch spacing to gain insight into the evolution of the molten pool morphology, surface roughness, and dimensional accuracy. The results show that the average width and depth of the molten pool, the lower surface roughness and dimensional deviation decrease with the increase of scanning speed and hatch spacing. The upper surface roughness is found to be almost constant under different processing parameters. The width and depth of the molten pool on powder-supported zone are larger than that of the molten pool on the solid-supported zone, while the width changes more significantly than that of depth. However, if the scanning speed is high enough, the width and depth of the molten pool and the lower surface roughness almost keep constant as the density is still high. Therefore, high dimensional accuracy and density as well as good surface quality can be achieved simultaneously by using high scanning speed during SLMed cellular lattice strut.

Investigation on Selective Laser Melting AlSi10Mg Cellular Lattice Strut: Molten Pool Morphology, Surface Roughness and Dimensional Accuracy.

Science.gov (United States)

Han, Xuesong; Zhu, Haihong; Nie, Xiaojia; Wang, Guoqing; Zeng, Xiaoyan

2018-03-07

AlSi10Mg inclined struts with angle of 45° were fabricated by selective laser melting (SLM) using different scanning speed and hatch spacing to gain insight into the evolution of the molten pool morphology, surface roughness, and dimensional accuracy. The results show that the average width and depth of the molten pool, the lower surface roughness and dimensional deviation decrease with the increase of scanning speed and hatch spacing. The upper surface roughness is found to be almost constant under different processing parameters. The width and depth of the molten pool on powder-supported zone are larger than that of the molten pool on the solid-supported zone, while the width changes more significantly than that of depth. However, if the scanning speed is high enough, the width and depth of the molten pool and the lower surface roughness almost keep constant as the density is still high. Therefore, high dimensional accuracy and density as well as good surface quality can be achieved simultaneously by using high scanning speed during SLMed cellular lattice strut.

Surface engineering of cardiovascular stent with endothelial cell selectivity for in vivo re-endothelialisation.

Science.gov (United States)

Wei, Yu; Ji, Ying; Xiao, Lin-Lin; Lin, Quan-kui; Xu, Jian-ping; Ren, Ke-feng; Ji, Jian

2013-04-01

The in vivo endothelialisation of materials provides a promising strategy for the rapid re-endothelialisation of a cardiovascular implantation. Although many studies have focused on improving the rapid endothelialisation through the immobilisation of bioactive molecules, it should be noted that the endothelial cells (ECs) will compete with other cell types in vivo. Thus, the efforts to partially enhance the EC growth without considering the cell competition might be misleading and meaningless in vivo. In this study, we demonstrated that the competitive growth of human umbilical vein endothelial cells (HUVECs) over human aortic smooth muscle cells (HASMCs) could be increased through the synergic action of the nonspecific resistance to phosphorylcholine and the specific recognition of the REDV peptide. Further in vivo data indicate that the competitive ability of ECs over SMCs, instead of the number of ECs, is a significantly more important criterion for the development of a pure endothelial layer in vivo and thus the attainment of a better anti-restenosis effect. Consequently, the surface tailoring of a stent to obtain high endothelial cell selectivity is likely an effective design criterion for in situ endothelialisation and a possible future solution for the problem of in-stent restenosis. Copyright © 2013 Elsevier Ltd. All rights reserved.

Disease-linked mutations in factor H reveal pivotal role of cofactor activity in self-surface-selective regulation of complement activation.

Science.gov (United States)

Kerr, Heather; Wong, Edwin; Makou, Elisavet; Yang, Yi; Marchbank, Kevin; Kavanagh, David; Richards, Anna; Herbert, Andrew P; Barlow, Paul N

2017-08-11

Spontaneous activation enables the complement system to respond very rapidly to diverse threats. This activation is efficiently suppressed by complement factor H (CFH) on self-surfaces but not on foreign surfaces. The surface selectivity of CFH, a soluble protein containing 20 complement-control protein modules (CCPs 1-20), may be compromised by disease-linked mutations. However, which of the several functions of CFH drives this self-surface selectivity remains unknown. To address this, we expressed human CFH mutants in Pichia pastoris We found that recombinant I62-CFH (protective against age-related macular degeneration) and V62-CFH functioned equivalently, matching or outperforming plasma-derived CFH, whereas R53H-CFH, linked to atypical hemolytic uremic syndrome (aHUS), was defective in C3bBb decay-accelerating activity (DAA) and factor I cofactor activity (CA). The aHUS-linked CCP 19 mutant D1119G-CFH had virtually no CA on (self-like) sheep erythrocytes ( E S ) but retained DAA. The aHUS-linked CCP 20 mutant S1191L/V1197A-CFH (LA-CFH) had dramatically reduced CA on E S but was less compromised in DAA. D1119G-CFH and LA-CFH both performed poorly at preventing complement-mediated hemolysis of E S PspCN, a CFH-binding Streptococcus pneumoniae protein domain, binds CFH tightly and increases accessibility of CCPs 19 and 20. PspCN did not improve the DAA of any CFH variant on E S Conversely, PspCN boosted the CA, on E S , of I62-CFH, R53H-CFH, and LA-CFH and also enhanced hemolysis protection by I62-CFH and LA-CFH. We conclude that CCPs 19 and 20 are critical for efficient CA on self-surfaces but less important for DAA. Exposing CCPs 19 and 20 with PspCN and thus enhancing CA on self-surfaces may reverse deficiencies of some CFH variants. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Energy loss spectroscopy applied to surface studies

International Nuclear Information System (INIS)

Lecante, J.

1975-01-01

The analysis of energy losses suffered by slow electrons (5 eV to 300 eV) back-scattered by single crystal surfaces appears to be a powerful method for surfaces studies. The inelastic scattering of these slow electrons limits their escape depth to the surface region which is defined here. After a review of the basic excitation processes due to the interaction between electrons and surfaces (phonons, plasmons and electronic transitions) a brief discussion is given about the instruments needed for this electron spectroscopy. Finally some experimental results are listed and it is shown that the comparison of the results given by ELS with other surface sensitive methods such as UPS is very fruitful and new information can be obtained [fr

Antibodies from malaria-exposed pregnant women recognize trypsin resistant epitopes on the surface of Plasmodium falciparum-infected erythrocytes selected for adhesion to chondroitin sulphate A

DEFF Research Database (Denmark)

Sharling, Lisa; Enevold, Anders; Sowa, Kordai M P

2004-01-01

of CSA binding and surface recognition of CSA selected parasites by serum IgG from malaria exposed pregnant women. Thus, the complete molecular definition of an antigenic P. falciparum erythrocyte surface protein that can be used as a malaria in pregnancy vaccine has not yet been achieved.......-specific antibodies induced as a result of pregnancy associated malaria (PAM). METHODS: Fluorescence activated cell sorting (FACS) was used to measure the levels of adult Scottish and Ghanaian male, and Ghanaian pregnant female plasma immunoglobulin G (IgG) that bind to the surface of infected erythrocytes. P....... falciparum infected erythrocytes selected for adhesion to CSA were found to express trypsin-resistant VSA that are the target of naturally acquired antibodies from pregnant women living in a malaria endemic region of Ghana. However in vitro adhesion to CSA and HA was relatively trypsin sensitive. An improved...

Selective scene perception deficits in a case of topographical disorientation.

Science.gov (United States)

Robin, Jessica; Lowe, Matthew X; Pishdadian, Sara; Rivest, Josée; Cant, Jonathan S; Moscovitch, Morris

2017-07-01

Topographical disorientation (TD) is a neuropsychological condition characterized by an inability to find one's way, even in familiar environments. One common contributing cause of TD is landmark agnosia, a visual recognition impairment specific to scenes and landmarks. Although many cases of TD with landmark agnosia have been documented, little is known about the perceptual mechanisms which lead to selective deficits in recognizing scenes. In the present study, we test LH, a man who exhibits TD and landmark agnosia, on measures of scene perception that require selectively attending to either the configural or surface properties of a scene. Compared to healthy controls, LH demonstrates perceptual impairments when attending to the configuration of a scene, but not when attending to its surface properties, such as the pattern of the walls or whether the ground is sand or grass. In contrast, when focusing on objects instead of scenes, LH demonstrates intact perception of both geometric and surface properties. This study demonstrates that in a case of TD and landmark agnosia, the perceptual impairments are selective to the layout of scenes, providing insight into the mechanism of landmark agnosia and scene-selective perceptual processes. Copyright © 2017 Elsevier Ltd. All rights reserved.

Novel types of anti-ecloud surfaces

CERN Document Server

Montero, I; Dávila, M E; Nistor, V; Galán, L; González, L A; Raboso, D; Costa Pinto, P; Taborelli, M; Caspers, F; Ulrich, U; Wolk, D

2013-01-01

In high power RF devices for space, secondary electron emission appears as the main parameter governing the multipactor effect and as well as the e-cloud in large accelerators. Critical experimental activities included development of coatings with low secondary electron emission yield (SEY) for steel (large accelerators) and aluminium (space applications). Coatings with surface roughness of high aspect ratio producing the so-call secondary emission suppression effect appear as the selected strategy. In this work a detailed study of the SEY of these technological coatings and also the experimental deposition methods (PVD and electrochemical) are presented. The coating-design approach selected for new low SEY coatings include rough metals (Ag, Au, Al), rough alloys (NEG), particulated and magnetized surfaces, and also graphene like coatings. It was found that surface roughness also mitigate the SEY deterioration due to aging processes.

An atomic force microscopy study on the transition from mushrooms to octopus surface ''micelles'' by changing the solvent quality

NARCIS (Netherlands)

Stamouli, A.; Pelletier, E.; Koutsos, V; van der Vegte, E.W.; Hadziioannou, G

1996-01-01

Atomic force microscopy (AFM) is used to study the behavior of a diblock copolymer onto a solid surface while the solvent quality is changed. In a first step, the copolymer poly(2-vinylpyridine)/polystyrene (P2VP/PS) is adsorbed onto mica from a selective solvent (the PS block is well solvated and

Effects of ion sputtering on semiconductor surfaces

International Nuclear Information System (INIS)

McGuire, G.E.

1978-01-01

Ion beam sputtering has been combined with Auger spectroscopy to study the effects of ion beams on semiconductor surfaces. Observations on the mass dependence of ion selective sputtering of two component systems are presented. The effects of ion implantation are explained in terms of atomic dilution. Experimental data are presented that illustrate the super-position of selective sputtering and implantation effects on the surface composition. Sample reduction from electron and ion beam interaction is illustrated. Apparent sample changes which one might observe from the effects of residual gas contamination and electric fields are also discussed. (Auth.)

TED Study of Si(113) Surfaces

Science.gov (United States)

Suzuki, T.; Minoda, H.; Tanishiro, Y.; Yagi, K.

A TED study of Si(113) surfaces was carried out. Reflections from the 3 × 2 reconstruction were seen at room temperature, while half-order reflections were very faint. The surface showed the phase transition between the 3 × 1 and the disordered (rough) structures at about 930°C. The (113) surface structure at room temperature was analyzed using TED intensity. Four kinds of structure models proposed previously, including both the 3 × 1 and the 3 × 2 reconstructed structures, were examined. The R-factors calculated using the energy-optimized atomic coordinates are not sufficiently small. After minimization of the R-factors, Dabrowski's 3 × 2 structure model is most agreeable, while Ranke's 3 × 1 and 3 × 2 structure models are not to be excluded. STM observation showed that the surface is composed of small domains of the 3 × 2 structure.

Immobilization of ionophore and surface characterization studies of the titanium(III) ion in a PVC-membrane sensor.

Science.gov (United States)

Rezayi, Majid; Heng, Lee Yook; Kassim, Anuar; Ahmadzadeh, Saeid; Abdollahi, Yadollah; Jahangirian, Hossein

2012-01-01

Novel ionophores comprising various hydroxide and amine structures were immobilized onto poly(vinyl chloride) (PVC) matrices, and these were examined to determine Ti(III) selectivity. To predict the selectivity of Ti(III), a PVC membrane was used to investigate the binding of Ti(III) to c-methylcalix[4]resorcinarene (CMCR). The study showed that the chelating ligand, CMCR, was coordinated selectively to Ti(III) at eight coordination sites involving the oxygen atoms at the interface of the membrane/solution. The membrane was prepared, based on CMCR as an ionophore, sodium tetrakis(4-fluorophenyl) borate (NaTFPB) as a lipophilic ionic additive, and dioctylphthalate (DOP) as a plasticizer. The immobilization of the ionophore and surface characterization studies revealed that the performance of CMCR-immobilized PVC was equivalent to that of mobile ionophores in supported liquid membranes (SLMs). The strengths of the ion-ionophore (CMCR-Ti(OH)(OH(2))(5) (2+)) interactions and the role of ionophores on membranes were studied via UV-Vis, Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and and X-ray diffraction (XRD).

Managing the Public Sector Research and Development Portfolio Selection Process: A Case Study of Quantitative Selection and Optimization

Science.gov (United States)

2016-09-01

PUBLIC SECTOR RESEARCH & DEVELOPMENT PORTFOLIO SELECTION PROCESS: A CASE STUDY OF QUANTITATIVE SELECTION AND OPTIMIZATION by Jason A. Schwartz...PUBLIC SECTOR RESEARCH & DEVELOPMENT PORTFOLIO SELECTION PROCESS: A CASE STUDY OF QUANTITATIVE SELECTION AND OPTIMIZATION 5. FUNDING NUMBERS 6...describing how public sector organizations can implement a research and development (R&D) portfolio optimization strategy to maximize the cost

Surface-Activated Coupling Reactions Confined on a Surface.

Science.gov (United States)

Dong, Lei; Liu, Pei Nian; Lin, Nian

2015-10-20

-functional theory (DFT) transition-state calculations have been used to shed light on reaction mechanisms and to unravel the trends of different surface materials. In this Account, we discuss recent progress made in two widely studied surface-confined coupling reactions, aryl-aryl (Ullmann-type) coupling and alkyne-alkyne (Glaser-type) coupling, and focus on surface activation effects. Combined experimental and theoretical studies on the same reactions taking place on different metal surfaces have clearly demonstrated that different surfaces not only reduce the reaction barrier differently and render different reaction pathways but also control the morphology of the reaction products and, to some degree, select the reaction products. We end the Account with a list of questions to be addressed in the future. Satisfactorily answering these questions may lead to using the surface-confined coupling reactions to synthesize predefined products with high yield.

Sum-frequency spectroscopic studies: I. Surface melting of ice, II. Surface alignment of polymers

Energy Technology Data Exchange (ETDEWEB)

Wei, Xing [Univ. of California, Berkeley, CA (United States)

2000-01-01

Surface vibrational spectroscopy via infrared-visible sum-frequency generation (SFG) has been established as a useful tool to study the structures of different kinds of surfaces and interfaces. This technique was used to study the (0001) face of hexagonal ice (Ih). SFG spectra in the O-H stretch frequency range were obtained at various sample temperatures. For the vapor(air)/ice interface, the degree of orientational order of the dangling OH bonds at the surface was measured as a function of temperature. Disordering sets in around 200 K and increases dramatically with temperature, which is strong evidence of surface melting of ice. For the other ice interfaces (silica/OTS/ice and silica/ice), a similar temperature dependence of the hydrogen bonded OH stretch peak was observed; the free OH stretch mode, however, appears to be different from that of the vapor (air)/ice interface due to interactions at the interfaces. The technique was also used to measure the orientational distributions of the polymer chains on a rubbed polyvinyl alcohol surface. Results show that the polymer chains at the surface appear to be well aligned by rubbing, and the adsorbed liquid crystal molecules are aligned, in turn, by the surface polymer chains. A strong correlation exists between the orientational distributions of the polymer chains and the liquid crystal molecules, indicating that the surface-induced bulk alignment of a liquid crystal film by rubbed polymer surfaces is via an orientational epitaxy-like mechanism. This thesis also contains studies on some related issues that are crucial to the above applications. An experiment was designed to measure SFG spectra in both reflection and transmission. The result confirms that SFG in reflection is generally dominated by the surface contribution. Another issue is the motional effect due to fast orientational motion of molecules at a surface or interface. Calculations show that the effect is significant if the molecular orientation varies

Role of surface studies in science and technology

Energy Technology Data Exchange (ETDEWEB)

Karkhanavala, M D [Bhabha Atomic Research Centre, Bombay (India). Chemistry Div.

1977-01-01

Reactivity of solids is influenced by the surface properties such as structure, dislocations and composition. Corrosion and erosion are essentially surface phenomena. Surface studies, therefore, assume importance in prevention and minimization of corrosion and erosion. Discussion is illustrated with examples drawn from the field of nuclear power reactor technology.

Electrochemical Control of Peptide Self-Organization on Atomically Flat Solid Surfaces: A Case Study with Graphite.

Science.gov (United States)

Seki, Takakazu; So, Christopher R; Page, Tamon R; Starkebaum, David; Hayamizu, Yuhei; Sarikaya, Mehmet

2018-02-06

The nanoscale self-organization of biomolecules, such as proteins and peptides, on solid surfaces under controlled conditions is an important issue in establishing functional bio/solid soft interfaces for bioassays, biosensors, and biofuel cells. Electrostatic interaction between proteins and surfaces is one of the most essential parameters in the adsorption and self-assembly of proteins on solid surfaces. Although the adsorption of proteins has been studied with respect to the electrochemical surface potential, the self-assembly of proteins or peptides forming well-organized nanostructures templated by lattice structure of the solid surfaces has not been studied in the relation to the surface potential. In this work, we utilize graphite-binding peptides (GrBPs) selected by the phage display method to investigate the relationship between the electrochemical potential of the highly ordered pyrolytic graphite (HOPG) and peptide self-organization forming long-range-ordered structures. Under modulated electrical bias, graphite-binding peptides form various ordered structures, such as well-ordered nanowires, dendritic structures, wavy wires, amorphous (disordered) structures, and islands. A systematic investigation of the correlation between peptide sequence and self-organizational characteristics reveals that the presence of the bias-sensitive amino acid modules in the peptide sequence has a significant effect on not only surface coverage but also on the morphological features of self-assembled structures. Our results show a new method to control peptide self-assembly by means of applied electrochemical bias as well as peptide design-rules for the construction of functional soft bio/solid interfaces that could be integrated in a wide range of practical implementations.

Surface and Interface Studies with Radioactive Ions

CERN Multimedia

Weber, A

2002-01-01

Investigations on the atomic scale of magnetic surfaces and magnetic multilayers were performed by Perturbed Angular Correlation (PAC) spectroscopy. The unique combination of the Booster ISOLDE facility equipped with a UHV beamline and the UHV chamber ASPIC (Apparatus for Surface Physics and Interfaces at CERN) is ideally suited for such microscopic studies. Main advantages are the choice of problem-oriented radioactive probes and the purity of mass-separated beams. The following results were obtained: $\\,$i) Magnetic hyperfine fields (B$_{hf}$) of Se on Fe, Co, Ni surfaces were determined. The results prompted a theoretical study on the B$_{hf}$ values of the 4sp-elements in adatom position on Ni and Fe, confirming our results and predicting unexpected behaviour for the other elements. $\\,$ii) Exemplarily we have determined B$_{hf}$ values of $^{111}$Cd at many different adsorption sites on Ni surfaces. We found a strong dependence on the coordination number of the probes. With decreasing coordination nu...

Soil aggregate stability and size-selective sediment transport with surface runoff as affected by organic residue amendment.

Science.gov (United States)

Shi, Pu; Arter, Christian; Liu, Xingyu; Keller, Martin; Schulin, Rainer

2017-12-31

Aggregate breakdown influences the availability of soil particles for size-selective sediment transport with surface runoff during erosive rainfall events. Organic matter management is known to affect aggregate stability against breakdown, but little is known about how this translates into rainfall-induced aggregate fragmentation and sediment transport under field conditions. In this study, we performed field experiments in which artificial rainfall was applied after pre-wetting on three pairs of arable soil plots (1.5×0.75m) six weeks after incorporating a mixture of grass and wheat straw into the topsoil of one plot in each pair (OI treatment) but not on the other plot (NI treatment). Artificial rainfall was applied for approximately 2h on each pair at an intensity of 49.1mmh -1 . In both treatments, discharge and sediment concentration in the discharge were correlated and followed a similar temporal pattern after the onset of surface runoff: After a sharp increase at the beginning both approached a steady state. But the onset of runoff was more delayed on the OI plots, and the discharge and sediment concentration were in average only roughly half as high on the OI as on the NI plots. With increasing discharge the fraction of coarse sediment increased. This relationship did not differ between the two treatments. Thus, due to the lower discharge, the fraction of fine particles in the exported sediment was larger in the runoff from the OI plots than from the NI plots. The later runoff onset and lower discharge rate was related to a higher initial aggregate stability on the OI plots. Terrestrial laser scanning proved to be a very valuable method to map changes in the micro-topography of the soil surfaces. It revealed a much less profound decrease in surface roughness on the OI than on the NI plots. Copyright © 2017 Elsevier B.V. All rights reserved.

Selective enhancement of surface-state emission and simultaneous quenching of interband transition in white-luminophor CdS nanocrystals using localized plasmon coupling

Energy Technology Data Exchange (ETDEWEB)

Ozel, Tuncay; Soganci, Ibrahim Murat; Nizamoglu, Sedat; Huyal, Ilkem Ozge; Mutlugun, Evren; Demir, Hilmi Volkan [Department of Physics, Department of Electrical and Electronics Engineering, Nanotechnology Research Center and Institute of Materials Science and Nanotechnology, Bilkent University, Ankara 06800 (Turkey); Sapra, Sameer; Gaponik, Nikolai; Eychmueller, Alexander [Physical Chemistry/Electrochemistry Group, Technische Universitaet Dresden, Bergstr. 66b, Dresden 01062 (Germany)], E-mail: volkan@bilkent.edu.tr

2008-08-15

We propose and demonstrate the controlled modification and selective enhancement of surface-state emission in white-luminophor CdS nanocrystals (NCs) by plasmon-coupling them with proximal metal nanostructures. By carefully designing nano-Ag films to match their localized plasmon resonance spectrally with the surface-state emission peak of CdS NCs, we experimentally show that the surface-state emission is substantially enhanced in the visible wavelength, while the interband (band-edge) transition at the shorter wavelength far away from the plasmon resonance is simultaneously significantly suppressed. With such plasmon tuning and consequent strong plasmon coupling specifically for the surface-state transitions, the surface-state emission is made stronger than the band-edge emission. This corresponds to an enhancement factor of 12.7-fold in the ratio of the surface-state peak emission to the band-edge peak emission of the plasmon-coupled film sample compared with that in solution. Such a plasmonic engineering of surface-state emission in trap-rich CdS white nanoluminophors holds great promise for future solid-state lighting.

Selective enhancement of surface-state emission and simultaneous quenching of interband transition in white-luminophor CdS nanocrystals using localized plasmon coupling

International Nuclear Information System (INIS)

Ozel, Tuncay; Soganci, Ibrahim Murat; Nizamoglu, Sedat; Huyal, Ilkem Ozge; Mutlugun, Evren; Demir, Hilmi Volkan; Sapra, Sameer; Gaponik, Nikolai; Eychmueller, Alexander

2008-01-01

We propose and demonstrate the controlled modification and selective enhancement of surface-state emission in white-luminophor CdS nanocrystals (NCs) by plasmon-coupling them with proximal metal nanostructures. By carefully designing nano-Ag films to match their localized plasmon resonance spectrally with the surface-state emission peak of CdS NCs, we experimentally show that the surface-state emission is substantially enhanced in the visible wavelength, while the interband (band-edge) transition at the shorter wavelength far away from the plasmon resonance is simultaneously significantly suppressed. With such plasmon tuning and consequent strong plasmon coupling specifically for the surface-state transitions, the surface-state emission is made stronger than the band-edge emission. This corresponds to an enhancement factor of 12.7-fold in the ratio of the surface-state peak emission to the band-edge peak emission of the plasmon-coupled film sample compared with that in solution. Such a plasmonic engineering of surface-state emission in trap-rich CdS white nanoluminophors holds great promise for future solid-state lighting

Computer simulation of the relationship between selected properties of laser remelted tool steel surface layer

Energy Technology Data Exchange (ETDEWEB)

Bonek, Mirosław, E-mail: miroslaw.bonek@polsl.pl; Śliwa, Agata; Mikuła, Jarosław

2016-12-01

Highlights: • Prediction of the properties of laser remelted surface layer with the use of FEM analysis. • The simulation was applied to determine the shape of molten pool of remelted surface. • Applying of numerical model MES for simulation of surface laser treatment to meaningfully shorten time of selection of optimum parameters. • An FEM model was established for the purpose of building a computer simulation. - Abstract: Investigations >The language in this paper has been slightly changed. Please check for clarity of thought, and that the meaning is still correct, and amend if necessary.include Finite Element Method simulation model of remelting of PMHSS6-5-3 high-speed steel surface layer using the high power diode laser (HPDL). The Finite Element Method computations were performed using ANSYS software. The scope of FEM simulation was determination of temperature distribution during laser alloying process at various process configurations regarding the laser beam power and method of powder deposition, as pre-coated past or surface with machined grooves. The Finite Element Method simulation was performed on five different 3-dimensional models. The model assumed nonlinear change of thermal conductivity, specific heat and density that were depended on temperature. The heating process was realized as heat flux corresponding to laser beam power of 1.4, 1.7 and 2.1 kW. Latent heat effects are considered during solidification. The molten pool is composed of the same material as the substrate and there is no chemical reaction. The absorptivity of laser energy was dependent on the simulated materials properties and their surface condition. The Finite Element Method simulation allows specifying the heat affected zone and the temperature distribution in the sample as a function of time and thus allows the estimation of the structural changes taking place during laser remelting process. The simulation was applied to determine the shape of molten pool and the

Genetic Diversity and Natural Selection in 42 kDa Region of Plasmodium vivax Merozoite Surface Protein-1 from China-Myanmar Endemic Border.

Science.gov (United States)

Zhou, Xia; Tambo, Ernest; Su, Jing; Fang, Qiang; Ruan, Wei; Chen, Jun-Hu; Yin, Ming-Bo; Zhou, Xiao-Nong

2017-10-01

Plasmodium vivax merozoite surface protein-1 (PvMSP1) gene codes for a major malaria vaccine candidate antigen. However, its polymorphic nature represents an obstacle to the design of a protective vaccine. In this study, we analyzed the genetic polymorphism and natural selection of the C-terminal 42 kDa fragment within PvMSP1 gene (Pv MSP142) from 77 P. vivax isolates, collected from imported cases of China-Myanmar border (CMB) areas in Yunnan province and the inland cases from Anhui, Yunnan, and Zhejiang province in China during 2009-2012. Totally, 41 haplotypes were identified and 30 of them were new haplotypes. The differences between the rates of non-synonymous and synonymous mutations suggest that PvMSP142 has evolved under natural selection, and a high selective pressure preferentially acted on regions identified of PvMSP133. Our results also demonstrated that PvMSP142 of P. vivax isolates collected on China-Myanmar border areas display higher genetic polymorphisms than those collected from inland of China. Such results have significant implications for understanding the dynamic of the P. vivax population and may be useful information towards China malaria elimination campaign strategies.

Molecular biology of the Chlamydia pneumoniae surface

DEFF Research Database (Denmark)

Christiansen, Gunna; Østergaard, Lars; Birkelund, Svend

1997-01-01

surface differs from that of Chlamydia trachomatis. In order to study the surface of C. pneumoniae we generated monoclonal antibodies (MAbs) against C. pneumoniae strain VR-1310 and selected 14 MAbs that reacted with the surface of C. pneumoniae. All MAbs reacted in immunoelectron microscopy...... with the surface of both whole C. pneumoniae VR-1310 elementary bodies and with purified sarcosyl extracted outer membrane complexes. However, only 2 of the MAbs reacted in immunoblotting with C. pneumoniae proteins and only with antigen that had not been heat treated in SDS-sample buffer. This indicates...

MSINDO quantum chemical modeling study of water molecule adsorption at nano-sized anatase TiO2 surfaces

International Nuclear Information System (INIS)

Wahab, Hilal S.; Bredow, Thomas; Aliwi, Salah M.

2008-01-01

In this work, we studied the adsorption of water molecule onto the (1 0 0), (0 1 0) and (0 0 1) surfaces of nano-sized anatase TiO 2 with semiempirical SCF MO method, MSINDO. The anatase TiO 2 particles are modeled with free clusters (TiO 2 ) n, where n = 20-80. Whereas, the surfaces have been modeled with two saturated clusters, Ti 21 O 58 H 32 and Ti 36 O 90 H 36 . The surface lattice fivefold coordinated titanium atoms (Ti 5C ), which represent the Lewis acid sites, are selected as adsorption centers. We also investigated the effect of TiO 2 cluster size on the computed band gap energy. Results reveal that the electronic properties of a cluster in the lowest excited state differ from that of the ground state. Furthermore, the MSINDO band gap energies of 3.68-3.77 eV for the anatase TiO 2 are in a fair accordance with other literature data. In agreement with other computational and experimental studies, the dissociated form of water molecule adsorption on anatase TiO 2 surfaces is always more stabilized than the molecular form

SFG and AFM Studies of Polymer Surface Monolayers

Science.gov (United States)

Somorjai, Gabor A.

2003-03-01

Sum frequency generation vibrational spectroscopy and atomic force microscopy techniques were utilized to study the structure and composition of polymer surfaces ranging from polyethylene and polypropylene to copolymers of polyurethane and polystyrene. The surface methyl groups aligned perpendicular to the surface above the glass transition temperature of polypropylene. Large side groups such as the phenyl group on polystyrene is also near the surface normal at the polymer-air interface. At the air interface hydrophobic groups are dominant on the polymer surface while at solid-water interface hydrophilic groups segregate to the surface. Minimizing surface energy is the cause of readjusting the surface composition at polymer-water interfaces as compared to polymer-air interfaces. Upon stretching the soft component of two-component polymer systems segregates to the surface and both the surface structure and the surface composition undergo reversible or irreversible changes depending on the magnitude of the stretch. Since the heart beat forces bio-polymers to stretch over 40 million times a year the molecular behavior due to stretching has important physiological consequences.

Progress in surface and membrane science

CERN Document Server

Cadenhead, D A

1981-01-01

Progress in Surface and Membrane Science, Volume 14 covers the advances in the study of surface and membrane science. The book discusses statistical thermodynamics of monolayer adsorption from gas and liquid mixtures on homogeneous and heterogeneous solid surfaces; and the structure of the boundary layers of liquids and its influence on the mass transfer in fine pores. The text then describes the coupling of ionic and non-electrolyte fluxes in ion selective membranes; the electrocatalytic properties of matalloporphins at the interface; and the adsorption from binary gas and liquid phases. Phas

Oxidation of clean silicon surfaces studied by four-point probe surface conductance measurements

DEFF Research Database (Denmark)

Petersen, Christian Leth; Grey, Francois; Aono, M.

1997-01-01

We have investigated how the conductance of Si(100)-(2 x 1) and Si(111)-(7 x 7) surfaces change during exposure to molecular oxygen. A monotonic decrease in conductance is seen as the (100) surfaces oxidizes. In contract to a prior study, we propose that this change is caused by a decrease in sur...

Platelet adhesion studies on dipyridamole coated polyurethane surfaces

Directory of Open Access Journals (Sweden)

Aldenhoff Y. B.J.

2003-06-01

Full Text Available Surface modification of polyurethanes (PUs by covalent attachment of dipyridamole (Persantinregistered is known to reduce adherence of blood platelets upon exposure to human platelet rich plasma (PRP. This effect was investigated in further detail. First platelet adhesion under static conditions was studied with four different biomaterial surfaces: untreated PU, PU immobilised with conjugate molecule 1, PU immobilised with conjugate molecule 2, and PU immobilised with conjugate molecule 3. In PU immobilised with 1 dipyridamole is directly linked to the surface, in PU immobilised with 2 there is a short hydrophilic spacer chain in between the surface and the dipyridamole, while conjugate molecule 3 is merely the spacer chain. Scanning electron microscopy (SEM was used to characterise platelet adhesion from human PRP under static conditions, and fluorescence imaging microscopy was used to study platelet adhesion from whole blood under flow. SEM experiments encompassed both density measurements and analysis of the morphology of adherent platelets. In the static experiments the surface immobilised with 2 showed the lowest platelet adherence. No difference between the three modified surfaces emerged from the flow experiments. The surfaces were also incubated with washed blood platelets and labeled with Oregon-Green Annexin V. No capture of Oregon-Green Annexin V was seen, implying that the adhered platelets did not expose any phosphatidyl serine at their exteriour surface.

Seventh BES [Basic Energy Sciences] catalysis and surface chemistry research conference

International Nuclear Information System (INIS)

1990-03-01

Research programs on catalysis and surface chemistry are presented. A total of fifty-seven topics are included. Areas of research include heterogeneous catalysis; catalysis in hydrogenation, desulfurization, gasification, and redox reactions; studies of surface properties and surface active sites; catalyst supports; chemical activation, deactivation; selectivity, chemical preparation; molecular structure studies; sorption and dissociation. Individual projects are processed separately for the data bases

Seventh BES (Basic Energy Sciences) catalysis and surface chemistry research conference

Energy Technology Data Exchange (ETDEWEB)

1990-03-01

Research programs on catalysis and surface chemistry are presented. A total of fifty-seven topics are included. Areas of research include heterogeneous catalysis; catalysis in hydrogenation, desulfurization, gasification, and redox reactions; studies of surface properties and surface active sites; catalyst supports; chemical activation, deactivation; selectivity, chemical preparation; molecular structure studies; sorption and dissociation. Individual projects are processed separately for the data bases. (CBS)

Reduced adhesion of macrophages on anodized titanium with select nanotube surface features

Directory of Open Access Journals (Sweden)

Balasubramanian K

2011-08-01

Full Text Available Amancherla Rajyalakshmi1, Batur Ercan2,3, K Balasubramanian1, Thomas J Webster2,31Non-Ferrous Materials Technology Development Centre, Hyderabad, India; 2School of Engineering, 3Department of Orthopedics, Brown University, Providence, RI, USAAbstract: One of the important prerequisites for a successful orthopedic implant apart from being osteoconductive is the elicitation of a favorable immune response that does not lead to the rejection of the implant by the host tissue. Anodization is one of the simplest surface modification processes used to create nanotextured and nanotubular features on metal oxides which has been shown to improve bone formation. Anodization of titanium (Ti leads to the formation of TiO2 nanotubes on the surface, and the presence of these nanotubes mimics the natural nanoscale features of bone, which in turn contributes to improved bone cell attachment, migration, and proliferation. However, inflammatory cell responses on anodized Ti remains to be tested. It is hypothesized that surface roughness and surface feature size on anodized Ti can be carefully manipulated to control immune cell (specifically, macrophages responses. Here, when Ti samples were anodized at 10 V in the presence of 1% hydrofluoric acid (HF for 1 minute, nanotextured (nonnanotube surfaces were created. When anodization of Ti samples was carried out with 1% HF for 10 minutes at 15 V, nanotubes with 40–50 nm diameters were formed, whereas at 20 V with 1% HF for 10 minutes, nanotubes with 60–70 nm diameters were formed. In this study, a reduced density of macrophages was observed after 24 hours of culture on nanotextured and nanotubular Ti samples which were anodized at 10, 15, and 20 V, compared with conventional unmodified Ti samples. This in vitro study thus demonstrated a reduced density of macrophages on anodized Ti, thereby providing further evidence of the greater efficacy of anodized Ti for orthopedic applications.Keywords: anodization, titanium

Size-Selective Oxidation of Aldehydes with Zeolite Encapsulated Gold Nanoparticles

DEFF Research Database (Denmark)

Højholt, Karen Thrane; Laursen, Anders Bo; Kegnæs, Søren

2011-01-01

Here, we report a synthesis and catalytic study of hybrid materials comprised of 1–3 nm sinter-stable Au nanoparticles in MFI-type zeolites. An optional post-treatment in aqua regia effectively remove Au from the external surfaces. The size-selective aerobic aldehyde oxidation verifies that the a......Here, we report a synthesis and catalytic study of hybrid materials comprised of 1–3 nm sinter-stable Au nanoparticles in MFI-type zeolites. An optional post-treatment in aqua regia effectively remove Au from the external surfaces. The size-selective aerobic aldehyde oxidation verifies...... that the active Au is accessible only through the zeolite micropores....

Selection as a learning experience: an exploratory study.

Science.gov (United States)

de Visser, Marieke; Laan, Roland F; Engbers, Rik; Cohen-Schotanus, Janke; Fluit, Cornelia

2018-01-01

Research on selection for medical school does not explore selection as a learning experience, despite growing attention for the learning effects of assessment in general. Insight in the learning effects allows us to take advantage of selection as an inclusive part of medical students' learning process to become competent professionals. The aims of this study at Radboud University Medical Center, the Netherlands, were 1) to determine whether students have learning experiences in the selection process, and, if so, what experiences; and 2) to understand what students need in order to utilize the learning effects of the selection process at the start of the formal curriculum. We used focus groups to interview 30 students admitted in 2016 about their learning experiences in the selection process. Thematic analysis was used to explore the outcomes of the interviews and to define relevant themes. In the selection process, students learned about the curriculum, themselves, their relation to others, and the profession they had been selected to enter, although this was not explicitly perceived as learning. Students needed a connection between selection and the curriculum as well as feedback to be able to really use their learning experiences for their further development. Medical school selection qualifies as a learning experience, and students as well as medical schools can take advantage of this. We recommend a careful design of the selection procedure, integrating relevant selection learning experiences into the formal curriculum, providing feedback and explicitly approaching the selection and the formal curriculum as interconnected contributors to students' development.

Restricted access magnetic materials prepared by dual surface modification for selective extraction of therapeutic drugs from biological fluids

Energy Technology Data Exchange (ETDEWEB)

Wang Yu; Wang Yuxia; Chen Lei [School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072 (China); Wan Qianhong, E-mail: qhwan@tju.edu.cn [School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072 (China)

2012-02-15

Magnetic porous particles with dual functionality have been prepared by a two-step procedure and evaluated as novel restricted access materials for extraction of therapeutic agents from biological fluids. The magnetic silica particles served as scaffolds were first modified with diol groups, which were then converted to octadecyl esters through reaction with stearoyl chloride. In the second step, the octadecyl esters on the exterior surface were hydrolyzed by the action of lipase to yield magnetic particles with hydrophobic reversed-phase ligands on the inner surface and biocompatible diol groups on the outer surface. The restricted access behavior of the resulting materials was confirmed by differential binding of small molecules such as methotrexate (MTX), leucovorin (LV) and folic acid (FA) relative to bovine serum albumin. While MTX, LV and FA were all bound to the magnetic particles with high affinity, the adsorption of the protein was markedly reduced due to size exclusion effect. The utility of the magnetic particles for sample preparation was tested in solid-phase extraction of MTX, LV and FA from spiked human serum and the effects of the SPE conditions on the recovery of the analytes were systematically studied. Moreover, the magnetic particle-based sample preparation procedure coupled with reversed-phase liquid chromatography analysis was validated in terms of specificity, linearity and reproducibility. The method was shown to be free from interference of endogenous compounds and linear over the concentration range of 0.5-10 {mu}g/mL for the three drugs studied. The limits of detection for the three drugs in serum were in the range of 0.160-0.302 {mu}g/mL. Reproducibility expressed as the RSD of the recovery for ten replicated extractions at three different concentrations was found to be less than 8.93%. With a unique combination of surface functionality with magnetic cores, the restricted access magnetic particles may be adapted in automated and high

Design of a Novel Miniaturized Frequency Selective Surface Based on 2.5-Dimensional Jerusalem Cross for 5G Applications

Directory of Open Access Journals (Sweden)

Peng Zhao

2018-01-01

Full Text Available A compact frequency selective surface (FSS for 5G applications has been designed based on 2.5-dimensional Jerusalem cross. The proposed element consists of two main parts: the successive segments of the metal traces placed alternately on the two surfaces of the substrate and the vertical vias connecting traces. Compared with previous published two-dimensional miniaturized elements, the transmission curves indicate a significant size reduction (1/26 wavelengths at the resonant frequency and exhibit good angular and polarization stabilities. Furthermore, a general equivalent circuit model is established to provide direct physical insight into the operating principle of this FSS. A prototype of the proposed FSS has been fabricated and measured, and the results validate this design.

Frequency selective surface based passive wireless sensor for structural health monitoring

International Nuclear Information System (INIS)

Jang, Sang-Dong; Kang, Byung-Woo; Kim, Jaehwan

2013-01-01

Wireless sensor networks or ubiquitous sensor networks are a promising technology giving useful information to people. In particular, the chipless passive wireless sensor is one of the most important developments in wireless sensor technology because it is compact and does not need a battery or chip for the sensor operation. So it has many possibilities for use in various types of sensor system with economical efficiency and robustness in harsh environmental conditions. This sensor uses an electromagnetic resonance frequency or phase angle shift associated with a geometrical change of the sensor tag or an impedance change of the sensor. In this paper, a chipless passive wireless structural health monitoring (SHM) sensor is made using a frequency selective surface (FSS). The cross type FSS is introduced, and its SHM principle is explained. The electromagnetic characteristics of the FSS are simulated in terms of transmission and reflection coefficients using simulation software, and an experimental verification is conducted. The electromagnetic characteristic change of the FSS in the presence of mechanical strain or a structural crack is investigated by means of simulation and experiment. Since large-area structures can be covered by deploying FSS, it is possible to detect the location of any cracks. (paper)

Positron beam studies of solids and surfaces: A summary

International Nuclear Information System (INIS)

Coleman, P.G.

2006-01-01

A personal overview is given of the advances in positron beam studies of solids and surfaces presented at the 10th International Workshop on Positron Beams, held in Doha, Qatar, in March 2005. Solids studied include semiconductors, metals, alloys and insulators, as well as biophysical systems. Surface studies focussed on positron annihilation-induced Auger electron spectroscopy (PAES), but interesting applications of positron-surface interactions in fields as diverse as semiconductor technology and studies of the interstellar medium serve to illustrate once again the breadth of scientific endeavour covered by slow positron beam investigations

Positron beam studies of solids and surfaces: A summary

Science.gov (United States)

Coleman, P. G.

2006-02-01

A personal overview is given of the advances in positron beam studies of solids and surfaces presented at the 10th International Workshop on Positron Beams, held in Doha, Qatar, in March 2005. Solids studied include semiconductors, metals, alloys and insulators, as well as biophysical systems. Surface studies focussed on positron annihilation-induced Auger electron spectroscopy (PAES), but interesting applications of positron-surface interactions in fields as diverse as semiconductor technology and studies of the interstellar medium serve to illustrate once again the breadth of scientific endeavour covered by slow positron beam investigations.

Passive Frequency Selective Surface Array as a Diffuser for Destroying Millimeter Wave Coherence

Directory of Open Access Journals (Sweden)

Saiful Islam

2008-01-01

Full Text Available This paper presents the design, construction, and testing of grounded frequency selective surface (FSS array as a diffuser for destroying millimeter wave coherence which is used to eliminate speckle in active millimeter wave imaging. To create stochastically independent illumination patterns, we proposed a diffuser based on random-phase distributions obtained by changing the incident frequency. The random-phase diffuser was obtained by mixing up the phase relations between the cells of a deterministic function (e.g., beam splitter. The slot length of FSS is the main design parameter used to optimize the phase shifting properties of the array. The critical parameters of the diffuser array design, such as phase relation with slot lengths, losses, and bandwidth, are discussed. We designed the FSS arrays with finite integral technique (FIT, fabricated by etching technique, and characterized the S-parameters with a free-space MVNA, and measured the radiation patterns with a BWO in motorized setup.

Concentration data for anthropogenic organic compounds in ground water, surface water, and finished water of selected community water systems in the United States, 2002-05

Science.gov (United States)

Carter, Janet M.; Delzer, Gregory C.; Kingsbury, James A.; Hopple, Jessica A.

2007-01-01

combustion-derived compounds; (10) personal care and domestic use products; (11) plant- or animal-derived biochemicals; (12) refrigerants and propellants; and (13) solvents. Source and finished water samples were collected during phase 2 and analyzed for constituents that were detected frequently during phase 1. This report presents concentration data for AOCs in ground water, surface water, and finished water of CWSs sampled for SWQA studies during 2002-05. Specifically, this report presents the analytical results of samples collected during phase 1 including (1) samples from 221 wells that were analyzed for 258 AOCs; (2) monthly samples from 9 surface-water sites that were analyzed for 258 AOCs during phase 1; and (3) samples from a subset of the wells and surface-water sites located in areas with substantial agricultural production that were analyzed for 3 additional pesticides and 16 pesticide degradates. Samples collected during phase 2 were analyzed for selected AOCs that were detected most frequently in source water during phase 1 sampling; analytical results for phase 2 are presented for (1) samples of source water and finished water from 94 wells; and (2) samples of source water and finished water samples that were collected monthly and during selected flow conditions at 8 surface-water sites. Results of quality-assurance/quality-control samples collected for SWQA studies during 2002-05 also are presented.

Optimum location of external markers using feature selection algorithms for real-time tumor tracking in external-beam radiotherapy: a virtual phantom study.

Science.gov (United States)

Nankali, Saber; Torshabi, Ahmad Esmaili; Miandoab, Payam Samadi; Baghizadeh, Amin

2016-01-08

In external-beam radiotherapy, using external markers is one of the most reliable tools to predict tumor position, in clinical applications. The main challenge in this approach is tumor motion tracking with highest accuracy that depends heavily on external markers location, and this issue is the objective of this study. Four commercially available feature selection algorithms entitled 1) Correlation-based Feature Selection, 2) Classifier, 3) Principal Components, and 4) Relief were proposed to find optimum location of external markers in combination with two "Genetic" and "Ranker" searching procedures. The performance of these algorithms has been evaluated using four-dimensional extended cardiac-torso anthropomorphic phantom. Six tumors in lung, three tumors in liver, and 49 points on the thorax surface were taken into account to simulate internal and external motions, respectively. The root mean square error of an adaptive neuro-fuzzy inference system (ANFIS) as prediction model was considered as metric for quantitatively evaluating the performance of proposed feature selection algorithms. To do this, the thorax surface region was divided into nine smaller segments and predefined tumors motion was predicted by ANFIS using external motion data of given markers at each small segment, separately. Our comparative results showed that all feature selection algorithms can reasonably select specific external markers from those segments where the root mean square error of the ANFIS model is minimum. Moreover, the performance accuracy of proposed feature selection algorithms was compared, separately. For this, each tumor motion was predicted using motion data of those external markers selected by each feature selection algorithm. Duncan statistical test, followed by F-test, on final results reflected that all proposed feature selection algorithms have the same performance accuracy for lung tumors. But for liver tumors, a correlation-based feature selection algorithm, in

Surface ionization mass spectrometry of opiates

International Nuclear Information System (INIS)

Usmanov, D.T.

2009-07-01

Key words: surface ionization, adsorption, heterogeneous reactions, surface ionization mass spectrometry, thermodesorption surface ionization spectroscopy, thermoemitter, opiates, extracts of biosamples. Subjects of study. The mass - spectrometric study of thermal - ion emission: surface ionization of opiates by on the surface of oxidized refractory metals. Purpose of work is to establish the regularities of surface ionization (SI) of multi-atomic molecule opiates and their mixtures develop the scientific base of SI methods for high sensitive and selective detection and analysis of these substances in the different objects, including biosamples. Methods of study: surface ionization mass spectrometry, thermodesorption surface ionization spectroscopy. The results obtained and their novelty. For the first time, SI of molecule opiates on the oxidized tungsten surface has been studied and their SI mass-spectra and temperature dependences of ion currents have been obtained, the characteristic heterogeneous reactions of an adsorbed molecules and the channels of monomolecular decays vibrationally-excited ions on their way in mass-spectrometry have been revealed, sublimation energy has been defined, the activation energy of E act , of these decays has been estimated for given period of time. Additivity of the SI mass-spectra of opiate mixtures of has been established under conditions of joint opiate adsorption. High selectivity of SI allows the extracts of biosamples to be analyzed without their preliminary chromatographic separation. The opiates are ionized by SI with high efficiency (from 34 C/mol to 112 C/mol), which provides high sensitivity of opiate detection by SI/MS and APTDSIS methods from - 10 -11 g in the samples under analysis. Practical value. The results of these studies create the scientific base for novel SI methods of high sensitive detection and analysis of the trace amounts of opiates in complicated mixtures, including biosamples without their preliminary

An ultrathin wide-band planar metamaterial absorber based on a fractal frequency selective surface and resistive film

International Nuclear Information System (INIS)

Fan Yue-Nong; Cheng Yong-Zhi; Nie Yan; Wang Xian; Gong Rong-Zhou

2013-01-01

We propose an ultrathin wide-band metamaterial absorber (MA) based on a Minkowski (MIK) fractal frequency selective surface and resistive film. This absorber consists of a periodic arrangement of dielectric substrates sandwiched with an MIK fractal loop structure electric resonator and a resistive film. The finite element method is used to simulate and analyze the absorption of the MA. Compared with the MA-backed copper film, the designed MA-backed resistive film exhibits an absorption of 90% at a frequency region of 2 GHz–20 GHz. The power loss density distribution of the MA is further illustrated to explain the mechanism of the proposed MA. Simulated absorptions at different incidence cases indicate that this absorber is polarization-insensitive and wide-angled. Finally, further simulated results indicate that the surface resistance of the resistive film and the dielectric constant of the substrate can affect the absorbing property of the MA. This absorber may be used in many military fields

Multiple trigger scintillators were installed: big ones covering the total surface of the sensor and several smaller ones. The former give a trigger for each beam particle. The latter are used to select a part of the sensor surface for efficiency measurements.

CERN Multimedia

Nooren, G.

2004-01-01

Multiple trigger scintillators were installed: big ones covering the total surface of the sensor and several smaller ones. The former give a trigger for each beam particle. The latter are used to select a part of the sensor surface for efficiency measurements.

A Simple Small Size and Low Cost Sensor Based on Surface Plasmon Resonance for Selective Detection of Fe(III

Directory of Open Access Journals (Sweden)

Nunzio Cennamo

2014-03-01

Full Text Available A simple, small size, and low cost sensor based on a Deferoxamine Self Assembled Monolayer (DFO-SAM and Surface Plasmon Resonance (SPR transduction, in connection with a Plastic Optical Fiber (POF, has been developed for the selective detection of Fe(III. DFO-SAM sensors based on appropriate electrochemical techniques can be frequently found in the scientific literature. In this work, we present the first example of a DFO-SAM sensor based on SPR in an optical fiber. The SPR sensing platform was realized by removing the cladding of a plastic optical fiber along half the circumference, spin coating a buffer of Microposit S1813 photoresist on the exposed core, and finally sputtering a thin gold film. The hydroxamate siderophore deferoxamine (DFO, having high binding affinity for Fe(III, is then used in its immobilized form, as self-assembled monolayer on the gold layer surface of the POF sensor. The results showed that the DFO-SAM-POF-sensor was able to sense the formation of the Fe(III/DFO complex in the range of concentrations between 1 μm and 50 μm with a linearity range from 0 to 30 μm of Fe(III. The selectivity of the sensor was also proved by interference tests.

A simple small size and low cost sensor based on surface plasmon resonance for selective detection of Fe(III).

Science.gov (United States)

Cennamo, Nunzio; Alberti, Giancarla; Pesavento, Maria; D'Agostino, Girolamo; Quattrini, Federico; Biesuz, Raffaela; Zeni, Luigi

2014-03-07

A simple, small size, and low cost sensor based on a Deferoxamine Self Assembled Monolayer (DFO-SAM) and Surface Plasmon Resonance (SPR) transduction, in connection with a Plastic Optical Fiber (POF), has been developed for the selective detection of Fe(III). DFO-SAM sensors based on appropriate electrochemical techniques can be frequently found in the scientific literature. In this work, we present the first example of a DFO-SAM sensor based on SPR in an optical fiber. The SPR sensing platform was realized by removing the cladding of a plastic optical fiber along half the circumference, spin coating a buffer of Microposit S1813 photoresist on the exposed core, and finally sputtering a thin gold film. The hydroxamate siderophore deferoxamine (DFO), having high binding affinity for Fe(III), is then used in its immobilized form, as self-assembled monolayer on the gold layer surface of the POF sensor. The results showed that the DFO-SAM-POF-sensor was able to sense the formation of the Fe(III)/DFO complex in the range of concentrations between 1 μm and 50 μm with a linearity range from 0 to 30 μm of Fe(III). The selectivity of the sensor was also proved by interference tests.

Thin film surface reconstruction analysis

Energy Technology Data Exchange (ETDEWEB)

Imperatori, P [CNR, Monterotondo Stazione, Rome (Italy). Istituto di Chimica dei materiali

1996-09-01

The study of the atomic structure of surfaces and interfaces is a fundamental step in the knowledge and the development of new materials. Among the several surface-sensitive techniques employed to characterise the atomic arrangements, grazing incidence x-ray diffraction (GIXD) is one of the most powerful. With a simple data treatment, based on the kinematical theory, and using the classical methods of x-ray bulk structure determination, it gives the atomic positions of atoms at a surface or an interface and the atomic displacements of subsurface layers for a complete determination of the structure. In this paper the main features of the technique will be briefly reviewed and selected of application to semiconductor and metal surfaces will be discussed.

Ti and Zr surfaces studied by molecular dynamics

International Nuclear Information System (INIS)

Pascuet, Maria I.; Passianot, Roberto C.; Monti, Ana M.

2003-01-01

The interaction between point defects technique and the (0001), (1-210), (10-10) surfaces in Ti and Zr is studied by the molecular dynamics technique. Both of metals are in the hexagonal structure and within a temperature range of 100 to 900 K. The atomic interactions are modeled by EAM-type many-body potentials, that were used previously in static simulations. New migration mechanisms are unraveled and others are verified with respect to those already proposed in the static studies. Also included is an analysis of the vacancy stability in the sub-surface layers of the prismatic surfaces. (author)

Surface analysis of the selective excimer laser patterning of a thin PEDOT:PSS film on flexible polymer films

Science.gov (United States)

Schaubroeck, David; De Smet, Jelle; Willems, Wouter; Cools, Pieter; De Geyter, Nathalie; Morent, Rino; De Smet, Herbert; Van Steenbeerge, Geert

2016-07-01

Fast patterning of highly conductive polymers like PEDOT:PSS (poly (3,4-ethylene dioxythiophene): polystyrene sulfonate) with lasers can contribute to the development of industrial production of liquid crystal displays on polymer foils. In this article, the selective UV laser patterning of a PEDOT:PSS film on flexible polymer films is investigated. Based on their optical properties, three polymer films are investigated: polyethylene terephthalate (PET), polymethyl methacrylate (PMMA) and cellulose triacetate (TAC). Ablation parameters for a 110 nm PEDOT:PSS film on these polymer films are optimized. A detailed study of the crater depth, topography and surface composition are provided using optical profilometry, scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), respectively. The electrical insulation of the lines is measured and correlated to the crater analyses for different laser settings. Finally, potential ablation parameters for each of the polymer films are derived.

Selective growth of two-dimensional phosphorene on catalyst surface.

Science.gov (United States)

Qiu, L; Dong, J C; Ding, F

2018-02-01

Although the study of black phosphorene (BP) and its isomers has attracted enormous attention, the method of synthesizing high-quality samples in a large area is still pending. Here we explore the potential of using the chemical vapor deposition method to synthesize large-area two-dimensional (2D) phosphorene films on metal surfaces. Our ab initio calculations show that BP can be synthesized by using tin (Sn) as a catalyst, while one of its isomers, blue phosphorene (BLP), is very possible to be synthesized by using most other metals, such as Ag and Au. Besides, our study also suggests that the large binding energy between the 2D phosphorene and the active metal substrate may prohibit the exfoliation of the 2D phosphorene for real applications and, therefore, tin, silver and gold are predicted to be the most suitable catalysts for the synthesis of BP and BLP.

Thermal and UV Hydrosilylation of Alcohol-Based Bifunctional Alkynes on Si (111) surfaces: How surface radicals influence surface bond formation.

Science.gov (United States)

Khung, Y L; Ngalim, S H; Scaccabarozi, A; Narducci, D

2015-06-12

Using two different hydrosilylation methods, low temperature thermal and UV initiation, silicon (111) hydrogenated surfaces were functionalized in presence of an OH-terminated alkyne, a CF3-terminated alkyne and a mixed equimolar ratio of the two alkynes. XPS studies revealed that in the absence of premeditated surface radical through low temperature hydrosilylation, the surface grafting proceeded to form a Si-O-C linkage via nucleophilic reaction through the OH group of the alkyne. This led to a small increase in surface roughness as well as an increase in hydrophobicity and this effect was attributed to the surficial etching of silicon to form nanosize pores (~1-3 nm) by residual water/oxygen as a result of changes to surface polarity from the grafting. Furthermore in the radical-free thermal environment, a mix in equimolar of these two short alkynes can achieve a high contact angle of ~102°, comparable to long alkyl chains grafting reported in literature although surface roughness was relatively mild (rms = ~1 nm). On the other hand, UV initiation on silicon totally reversed the chemical linkages to predominantly Si-C without further compromising the surface roughness, highlighting the importance of surface radicals determining the reactivity of the silicon surface to the selected alkynes.

Roka Listeria detection method using transcription mediated amplification to detect Listeria species in select foods and surfaces. Performance Tested Method(SM) 011201.

Science.gov (United States)

Hua, Yang; Kaplan, Shannon; Reshatoff, Michael; Hu, Ernie; Zukowski, Alexis; Schweis, Franz; Gin, Cristal; Maroni, Brett; Becker, Michael; Wisniewski, Michele

2012-01-01

The Roka Listeria Detection Assay was compared to the reference culture methods for nine select foods and three select surfaces. The Roka method used Half-Fraser Broth for enrichment at 35 +/- 2 degrees C for 24-28 h. Comparison of Roka's method to reference methods requires an unpaired approach. Each method had a total of 545 samples inoculated with a Listeria strain. Each food and surface was inoculated with a different strain of Listeria at two different levels per method. For the dairy products (Brie cheese, whole milk, and ice cream), our method was compared to AOAC Official Method(SM) 993.12. For the ready-to-eat meats (deli chicken, cured ham, chicken salad, and hot dogs) and environmental surfaces (sealed concrete, stainless steel, and plastic), these samples were compared to the U.S. Department of Agriculture/Food Safety and Inspection Service-Microbiology Laboratory Guidebook (USDA/FSIS-MLG) method MLG 8.07. Cold-smoked salmon and romaine lettuce were compared to the U.S. Food and Drug Administration/Bacteriological Analytical Manual, Chapter 10 (FDA/BAM) method. Roka's method had 358 positives out of 545 total inoculated samples compared to 332 positive for the reference methods. Overall the probability of detection analysis of the results showed better or equivalent performance compared to the reference methods.

Mechanism for selective growth in electrical steel

Science.gov (United States)

Oh, Eun Jee; Heo, Nam Hoe; Kwon, Se Kyun; Koo, Yang Mo

2018-01-01

Through the competitive selective growth process between {100}, {110}, and {111} grains during final annealing which is governed by the primary grain size and the surface segregation concentration of sulfur, the sharp {110} annealing texture can be developed in a C-and Al-free Fe-3%Si-0.1%Mn electrical steel. Generally, the selective growth of the {110} grains occurs actively under the low surface segregation concentration of sulfur. In spite of the surface energy disadvantage, the selective growth of a {hkl} grain can however occur, if the {hkl} grain size is larger than the critical grain size linearly proportional to the strip thickness.

Study the Postbuckling of Hexagonal Piezoelectric Nanowires with Surface Effect

Directory of Open Access Journals (Sweden)

O. Rahmani

2014-04-01

Full Text Available Piezoelectric nanobeams having circular, rectangular and hexagonal cross-sections are synthesized and used in various Nano structures; however, piezoelectric nanobeams with hexagonal cross-sections have not been studied in detail. In particular, the physical mechanisms of the surface effect and the role of surface stress, surface elasticity and surface piezoelectricity have not been discussed thoroughly. The present study investigated post-buckling behavior of piezoelectric nanobeams by examining surface effects. The energy method was applied to post-buckling of hexagonal nanobeams and the critical buckling voltage and amplitude are derived analytically from bulk and surface material properties and geometric factors.

Modern methods of studying surfaces and their application to glasses

International Nuclear Information System (INIS)

Rauschenbach, B.; Haehnert, M.

1977-05-01

In the works are demonstrated modern methods for study of solid surfaces and its use of glasses. Study of the interaction of ions, electrons and photons with the glass surface provides information about the composition of the surface and its structure on an atomic scale. A qualitative analysis of a surface can be made with the aid of the Auger electron spectroscopy (AES) and the electron spectroscopy for chemical analysis (ESCA) and with the ion scattering (ISS and RBS) and the secondary ion mass spectrometry (SIMS). The structure of a surface can be studied by means of ion scattering and low-energy electron diffraction (LEED) and the topography of a surface by means of scanning electron microscopy (SEM). The ellipsometry is generally confined to measuring the thickness of very thin layers. The application these methods to the glass surfaces is demonstrated on series of examples. (author)

Surface diffusion studies by optical diffraction techniques

International Nuclear Information System (INIS)

Xiao, X.D.

1992-11-01

The newly developed optical techniques have been combined with either second harmonic (SH) diffraction or linear diffraction off a monolayer adsorbate grating for surface diffusion measurement. Anisotropy of surface diffusion of CO on Ni(l10) was used as a demonstration for the second harmonic dim reaction method. The linear diffraction method, which possesses a much higher sensitivity than the SH diffraction method, was employed to study the effect of adsorbate-adsorbate interaction on CO diffusion on Ni(l10) surface. Results showed that only the short range direct CO-CO orbital overlapping interaction influences CO diffusion but not the long range dipole-dipole and CO-NI-CO interactions. Effects of impurities and defects on surface diffusion were further explored by using linear diffraction method on CO/Ni(110) system. It was found that a few percent S impurity can alter the CO diffusion barrier height to a much higher value through changing the Ni(110) surface. The point defects of Ni(l10) surface seem to speed up CO diffusion significantly. A mechanism with long jumps over multiple lattice distance initiated by CO filled vacancy is proposed to explain the observed defect effect

Study on Surface Integrity of AISI 1045 Carbon Steel when machined by Carbide Cutting Tool under wet conditions

Directory of Open Access Journals (Sweden)

Tamin N. Fauzi

2017-01-01

Full Text Available This paper presents the evaluation of surface roughness and roughness profiles when machining carbon steel under wet conditions with low and high cutting speeds. The workpiece materials and cutting tools selected in this research were AISI 1045 carbon steel and canela carbide inserts graded PM25, respectively. The cutting tools undergo machining tests by CNC turning operations and their performances were evaluated by their surface roughness value and observation of the surface roughness profile. The machining tests were held at varied cutting speeds of 35 to 53 m/min, feed rate of 0.15 to 0.50 mm/rev and a constant depth of cut of 1 mm. From the analysis, it was found that surface roughness increased as the feed rate increased. Varian of surface roughness was suspected due to interaction between cutting speeds and feed rates as well as nose radius conditions; whether from tool wear or the formation of a built-up edge. This study helps us understand the effect of cutting speed and feed rate on surface integrity, when machining AISI 1045 carbon steel using carbide cutting tools, under wet cutting conditions.

A density functional theory study of the adsorption behaviour of CO{sub 2} on Cu{sub 2}O surfaces

Energy Technology Data Exchange (ETDEWEB)

Mishra, Abhishek Kumar, E-mail: akmishra@ddn.upes.ac.in, E-mail: abhishek.mishra@ucl.ac.uk, E-mail: deleeuwn@cardiff.ac.uk [Research & Development, University of Petroleum and Energy Studies (UPES), Bidholi, Dehradun 248007 (India); Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ (United Kingdom); Roldan, Alberto [School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT (United Kingdom); Leeuw, Nora H. de, E-mail: akmishra@ddn.upes.ac.in, E-mail: abhishek.mishra@ucl.ac.uk, E-mail: deleeuwn@cardiff.ac.uk [Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ (United Kingdom); School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT (United Kingdom)

2016-07-28

Copper has many applications, particularly in electro-catalysis, where the oxidation state of the copper electrode plays a significant role in the selectivity towards products. Although copper-based materials have clear potential as catalysts in the reduction of CO{sub 2} and conversion to products, fundamental understanding of CO{sub 2} adsorption and activation on different copper oxide surfaces is still limited. We have used DFT+U methodology to study the surface reconstruction of the three most exposed (111), (110), and (001) surfaces of Cu{sub 2}O with different possible terminations. Considering several adsorbate geometries, we have investigated CO{sub 2} adsorption on five different possible terminations and proposed eight different configurations in which CO{sub 2} binds with the surface. Similar to earlier findings, CO{sub 2} binds weakly with the most stable Cu{sub 2}O(111):O surface showing no molecular activation, whereas a number of other surfaces, which can appear in the Cu{sub 2}O particles morphology, show stronger binding as well as activation of the CO{sub 2} molecule. Different CO{sub 2} coverages were studied and a detailed structural and electronic charge analysis is presented. The activation of the CO{sub 2} molecule is characterized by structural transformations and charge transfer between the surface and the CO{sub 2} molecule, which is further confirmed by considerable red shifts in the vibrational frequencies.

The sorption of uranium(VI) and neptunium(V) onto surfaces of selected metal oxides and alumosilicates studied by in situ vibrational spectroscopy

International Nuclear Information System (INIS)

Mueller, Katharina

2010-05-01

polymerization is deduced. Moreover, in contrast to TiO 2 , the appearance of ternary U(VI) carbonate complexes on the γ-Al 2 O 3 surface is suggested. The first results of the surface reactions on more complex, naturally occurring minerals (kaolinite, muscovite and biotite) show the formation of U(VI) inner-sphere sorption complexes. These findings are supported by the spectral information of the metal oxide surfaces. In this work, first spectroscopic results from sorption of aqueous Np(V) on solid mineral phases are provided. It is shown that stable inner-sphere surface species of NpO 2 + are formed on TiO 2 . Outer-sphere complexation is found to play a minor role due to the pH independence of the sorption species throughout the pH range 4 - 7.6. The comparative spectroscopic experiments of Np(V) sorption onto TiO 2 , SiO 2 , and ZnO indicate structurally similar bidentate surface complexes. The multiplicity of IR spectroscopic experiments carried out within this study yields a profound collection of spectroscopic data which will be used as references for future investigations of more complex sorption systems in aqueous solution. Furthermore, from a methodological point of view, this study comprehensively extends the application of ATR FT-IR spectroscopic experiments to a wide range in the field of radioecology. The results obtained in this work contribute to a better understanding of the geochemical interactions of actinides, in particular U(VI) and Np(V/VI), in the environment. Consequently, more reliable predictions of actinides migration which are essential for the safety assessment of nuclear waste repositories can be performed.

Strong Selective Adsorption of Polymers.

Science.gov (United States)

Ge, Ting; Rubinstein, Michael

2015-06-09

A scaling theory is developed for selective adsorption of polymers induced by the strong binding between specific monomers and complementary surface adsorption sites. By "selective" we mean specific attraction between a subset of all monomers, called "sticky", and a subset of surface sites, called "adsorption sites". We demonstrate that, in addition to the expected dependence on the polymer volume fraction ϕ bulk in the bulk solution, selective adsorption strongly depends on the ratio between two characteristic length scales, the root-mean-square distance l between neighboring sticky monomers along the polymer, and the average distance d between neighboring surface adsorption sites. The role of the ratio l / d arises from the fact that a polymer needs to deform to enable the spatial commensurability between its sticky monomers and the surface adsorption sites for selective adsorption. We study strong selective adsorption of both telechelic polymers with two end monomers being sticky and multisticker polymers with many sticky monomers between sticky ends. For telechelic polymers, we identify four adsorption regimes at l / d 1, we expect that the adsorption layer at exponentially low ϕ bulk consists of separated unstretched loops, while as ϕ bulk increases the layer crosses over to a brush of extended loops with a second layer of weakly overlapping tails. For multisticker chains, in the limit of exponentially low ϕ bulk , adsorbed polymers are well separated from each other. As l / d increases, the conformation of an individual polymer changes from a single-end-adsorbed "mushroom" to a random walk of loops. For high ϕ bulk , adsorbed polymers at small l / d are mushrooms that cover all the adsorption sites. At sufficiently large l / d , adsorbed multisticker polymers strongly overlap. We anticipate the formation of a self-similar carpet and with increasing l / d a two-layer structure with a brush of loops covered by a self-similar carpet. As l / d exceeds the

Improved bioactivity of selective laser melting titanium: Surface modification with micro-/nano-textured hierarchical topography and bone regeneration performance evaluation

Energy Technology Data Exchange (ETDEWEB)

Xu, Jia-yun [Department of Oral Implantology, Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Stomatology, Guangzhou 510055 (China); Chen, Xian-shuai; Zhang, Chun-yu [Guangzhou Institute of Advanced Technology, Chinese Academy of Science, Guangzhou 511458 (China); Liu, Yun; Wang, Jing [Department of Oral Implantology, Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Stomatology, Guangzhou 510055 (China); Deng, Fei-long, E-mail: drdfl@163.com [Department of Oral Implantology, Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Stomatology, Guangzhou 510055 (China)

2016-11-01

Selective laser melting (SLM) titanium requires surface modification to improve its bioactivity. The microrough surface of it can be utilized as the micro primary substrate to create a micro-/nano-textured topography for improved bone regeneration. In this study, the microrough SLM titanium substrate was optimized by sandblasting, and nano-porous features of orderly arranged nanotubes and disorderly arranged nanonet were produced by anodization (SAN) and alkali-heat treatment (SAH), respectively. The results were compared with the control group of an untreated surface (native-SLM) and a microtopography only surface treated by acid etching (SLA). The effects of the different topographies on cell functions and bone formation performance were evaluated in vitro and in vivo. It was found that micro-/nano-textured topographies of SAN and SAH showed enhanced cell behaviour relative to the microtopography of SLA with significantly higher proliferation on the 1st, 3rd, 5th and 7th day (P < 0.05) and higher total protein contents on the 14th day (P < 0.05). In vivo, SAN and SAH formed more successively regenerated bone, which resulted in higher bone-implant contact (BIC%) and bone-bonding force than native-SLM and SLA. In addition, the three-dimensional nanonet of SAH was expected to be more similar to native extracellular matrix (ECM) and thus led to better bone formation. The alkaline phosphatase activity of SAH was significantly higher than the other three groups at an earlier stage of the 7th day (P < 0.05) and the BIC% was nearly double that of native-SLM and SLA in the 8th week. In conclusion, the addition of nano-porous features on the microrough SLM titanium surface is effective in improving the bioactivity and bone regeneration performance, in which the ECM-like nanonet with a disorderly arranged biomimetic feature is suggested to be more efficient than nanotubes. - Highlights: • SLM titanium is modified by adding nano-porous features to the microrough substrate

Improved bioactivity of selective laser melting titanium: Surface modification with micro-/nano-textured hierarchical topography and bone regeneration performance evaluation

International Nuclear Information System (INIS)

Xu, Jia-yun; Chen, Xian-shuai; Zhang, Chun-yu; Liu, Yun; Wang, Jing; Deng, Fei-long

2016-01-01

Selective laser melting (SLM) titanium requires surface modification to improve its bioactivity. The microrough surface of it can be utilized as the micro primary substrate to create a micro-/nano-textured topography for improved bone regeneration. In this study, the microrough SLM titanium substrate was optimized by sandblasting, and nano-porous features of orderly arranged nanotubes and disorderly arranged nanonet were produced by anodization (SAN) and alkali-heat treatment (SAH), respectively. The results were compared with the control group of an untreated surface (native-SLM) and a microtopography only surface treated by acid etching (SLA). The effects of the different topographies on cell functions and bone formation performance were evaluated in vitro and in vivo. It was found that micro-/nano-textured topographies of SAN and SAH showed enhanced cell behaviour relative to the microtopography of SLA with significantly higher proliferation on the 1st, 3rd, 5th and 7th day (P < 0.05) and higher total protein contents on the 14th day (P < 0.05). In vivo, SAN and SAH formed more successively regenerated bone, which resulted in higher bone-implant contact (BIC%) and bone-bonding force than native-SLM and SLA. In addition, the three-dimensional nanonet of SAH was expected to be more similar to native extracellular matrix (ECM) and thus led to better bone formation. The alkaline phosphatase activity of SAH was significantly higher than the other three groups at an earlier stage of the 7th day (P < 0.05) and the BIC% was nearly double that of native-SLM and SLA in the 8th week. In conclusion, the addition of nano-porous features on the microrough SLM titanium surface is effective in improving the bioactivity and bone regeneration performance, in which the ECM-like nanonet with a disorderly arranged biomimetic feature is suggested to be more efficient than nanotubes. - Highlights: • SLM titanium is modified by adding nano-porous features to the microrough substrate

Study of Magnetohydrodynamic Surface Waves on Liquid Gallium

Energy Technology Data Exchange (ETDEWEB)

Hantao Ji; William Fox; David Pace; H.L. Rappaport

2004-05-13

Magnetohydrodynamic (MHD) surface waves on liquid gallium are studied theoretically and experimentally in the small magnetic Reynolds number limit. A linear dispersion relation is derived when a horizontal magnetic field and a horizontal electric current is imposed. No wave damping is found in the shallow liquid limit while waves always damp in the deep liquid limit with a magnetic field parallel to the propagation direction. When the magnetic field is weak, waves are weakly damped and the real part of the dispersion is unaffected, while in the opposite limit waves are strongly damped with shortened wavelengths. In a table-top experiment, planar MHD surface waves on liquid gallium are studied in detail in the regime of weak magnetic field and deep liquid. A non-invasive diagnostic accurately measures surface waves at multiple locations by reflecting an array of lasers off the surface onto a screen, which is recorded by an Intensified-CCD camera. The measured dispersion relation is consistent with the linear theory with a reduced surface tension likely due to surface oxidation. In excellent agreement with linear theory, it is observed that surface waves are damped only when a horizontal magnetic field is imposed parallel to the propagation direction. No damping is observed under a perpendicular magnetic field. The existence of strong wave damping even without magnetic field suggests the importance of the surface oxide layer. Implications to the liquid metal wall concept in fusion reactors, especially on the wave damping and a Rayleigh-Taylor instability when the Lorentz force is used to support liquid metal layer against gravity, are discussed.

Study of Magnetohydrodynamic Surface Waves on Liquid Gallium

International Nuclear Information System (INIS)

Hantao Ji; William Fox; David Pace; Rappaport, H.L.

2004-01-01

Magnetohydrodynamic (MHD) surface waves on liquid gallium are studied theoretically and experimentally in the small magnetic Reynolds number limit. A linear dispersion relation is derived when a horizontal magnetic field and a horizontal electric current is imposed. No wave damping is found in the shallow liquid limit while waves always damp in the deep liquid limit with a magnetic field parallel to the propagation direction. When the magnetic field is weak, waves are weakly damped and the real part of the dispersion is unaffected, while in the opposite limit waves are strongly damped with shortened wavelengths. In a table-top experiment, planar MHD surface waves on liquid gallium are studied in detail in the regime of weak magnetic field and deep liquid. A non-invasive diagnostic accurately measures surface waves at multiple locations by reflecting an array of lasers off the surface onto a screen, which is recorded by an Intensified-CCD camera. The measured dispersion relation is consistent with the linear theory with a reduced surface tension likely due to surface oxidation. In excellent agreement with linear theory, it is observed that surface waves are damped only when a horizontal magnetic field is imposed parallel to the propagation direction. No damping is observed under a perpendicular magnetic field. The existence of strong wave damping even without magnetic field suggests the importance of the surface oxide layer. Implications to the liquid metal wall concept in fusion reactors, especially on the wave damping and a Rayleigh-Taylor instability when the Lorentz force is used to support liquid metal layer against gravity, are discussed

Influence of Inherent Surface and Internal Defects on Mechanical Properties of Additively Manufactured Ti6Al4V Alloy: Comparison between Selective Laser Melting and Electron Beam Melting.

Science.gov (United States)

Fousová, Michaela; Vojtěch, Dalibor; Doubrava, Karel; Daniel, Matěj; Lin, Chiu-Feng

2018-03-31

Additive manufacture (AM) appears to be the most suitable technology to produce sophisticated, high quality, lightweight parts from Ti6Al4V alloy. However, the fatigue life of AM parts is of concern. In our study, we focused on a comparison of two techniques of additive manufacture-selective laser melting (SLM) and electron beam melting (EBM)-in terms of the mechanical properties during both static and dynamic loading. All of the samples were untreated to focus on the influence of surface condition inherent to SLM and EBM. The EBM samples were studied in the as-built state, while SLM was followed by heat treatment. The resulting similarity of microstructures led to comparable mechanical properties in tension, but, due to differences in surface roughness and specific internal defects, the fatigue strength of the EBM samples reached only half the value of the SLM samples. Higher surface roughness that is inherent to EBM contributed to multiple initiations of fatigue cracks, while only one crack initiated on the SLM surface. Also, facets that were formed by an intergranular cleavage fracture were observed in the EBM samples.

Influence of Inherent Surface and Internal Defects on Mechanical Properties of Additively Manufactured Ti6Al4V Alloy: Comparison between Selective Laser Melting and Electron Beam Melting

Directory of Open Access Journals (Sweden)

Michaela Fousová

2018-03-01

Full Text Available Additive manufacture (AM appears to be the most suitable technology to produce sophisticated, high quality, lightweight parts from Ti6Al4V alloy. However, the fatigue life of AM parts is of concern. In our study, we focused on a comparison of two techniques of additive manufacture—selective laser melting (SLM and electron beam melting (EBM—in terms of the mechanical properties during both static and dynamic loading. All of the samples were untreated to focus on the influence of surface condition inherent to SLM and EBM. The EBM samples were studied in the as-built state, while SLM was followed by heat treatment. The resulting similarity of microstructures led to comparable mechanical properties in tension, but, due to differences in surface roughness and specific internal defects, the fatigue strength of the EBM samples reached only half the value of the SLM samples. Higher surface roughness that is inherent to EBM contributed to multiple initiations of fatigue cracks, while only one crack initiated on the SLM surface. Also, facets that were formed by an intergranular cleavage fracture were observed in the EBM samples.

Surface studies of tungsten erosion and deposition in JT-60U

International Nuclear Information System (INIS)

Ueda, Y.; Fukumoto, M.; Nishikawa, M.; Tanabe, T.; Miya, N.; Arai, T.; Masaki, K.; Ishimoto, Y.; Tsuzuki, K.; Asakura, N.

2007-01-01

In order to study tungsten erosion and migration in JT-60U, 13 W tiles have been installed in the outer divertor region and tungsten deposition on graphite tiles was measured. Dense local tungsten deposition was observed on a CFC tile toroidally adjacent to the W tiles, which resulted from prompt ionization and short range migration of tungsten along field lines. Tungsten deposition with relatively high surface density was found on an inner divertor tile around standard inner strike positions and on an outer wing tile of a dome. On the outer wing tile, tungsten deposition was relatively high compared with carbon deposition. In addition, roughly uniform tungsten depth distribution near the upper edge of the inner divertor tile was observed. This could be due to lift-up of strike point positions in selected 25 shots and tungsten flow in the SOL plasma

IMPACT OF VIBRATORY AND ROTATIONAL SHOT PEENING ONTO SELECTED PROPERTIES OF TITANIUM ALLOY SURFACE LAYER

Directory of Open Access Journals (Sweden)

Kazimierz Zaleski

2014-06-01

Full Text Available This study presents the results of tests on impact of vibratory and rotational shot peening of the Ti6A12Mo2Cr titanium alloy onto the processed object surface roughness and surface layer microhardness. The external surfaces of ring-shaped samples were shot peened. The preceding process consisted of turning with a cubic boron nitride blade knife. Steel beads, having a diameter of 6 mm, were used as a processing medium. The variable parameters of shot peening were vibrator amplitude and shot peening time. The range of recommended technological parameters for vibratory and rotational shot peening was determined. As a result of shot peening, the surface roughness could be reduced by approximately 4 times and the surface layer could be hardened to the depth of approximately 0.4 mm.

Study on Surface Permeability of Concrete under Immersion

OpenAIRE

Liu, Jun; Xing, Feng; Dong, Biqin; Ma, Hongyan; Pan, Dong

2014-01-01

In this paper, concrete specimens are immersed in ultrapure water, to study the evolutions of surface permeability, pore structure and paste microstructure following the prolonging of immersion period. According to the results, after 30-day immersion, the surface permeability of concrete becomes higher as compared with the value before immersion. However, further immersion makes the surface permeability decrease, so that the value measured after 150-day immersion is only half that measured af...

Modeling and experimental study of oil/water contact angle on biomimetic micro-parallel-patterned self-cleaning surfaces of selected alloys used in water industry

Energy Technology Data Exchange (ETDEWEB)

Nickelsen, Simin; Moghadam, Afsaneh Dorri, E-mail: afsaneh@uwm.edu; Ferguson, J.B.; Rohatgi, Pradeep

2015-10-30

Graphical abstract: - Highlights: • Wetting behavior of four metallic materials as a function of surface roughness has been studied. • A model to predict the abrasive particle size and water/oil contact angles relationship is proposed. • Active wetting regime is determined in different materials using the proposed model. - Abstract: In the present study, the wetting behavior of surfaces of various common metallic materials used in the water industry including C84400 brass, commercially pure aluminum (99.0% pure), Nickle–Molybdenum alloy (Hastelloy C22), and 316 Stainless Steel prepared by mechanical abrasion and contact angles of several materials after mechanical abrasion were measured. A model to estimate roughness factor, R{sub f}, and fraction of solid/oil interface, ƒ{sub so}, for surfaces prepared by mechanical abrasion is proposed based on the assumption that abrasive particles acting on a metallic surface would result in scratches parallel to each other and each scratch would have a semi-round cross-section. The model geometrically describes the relation between sandpaper particle size and water/oil contact angle predicted by both the Wenzel and Cassie–Baxter contact type, which can then be used for comparison with experimental data to find which regime is active. Results show that brass and Hastelloy followed Cassie–Baxter behavior, aluminum followed Wenzel behavior and stainless steel exhibited a transition from Wenzel to Cassie–Baxter. Microstructural studies have also been done to rule out effects beyond the Wenzel and Cassie–Baxter theories such as size of structural details.

Single lump breast surface stress assessment study

Science.gov (United States)

Vairavan, R.; Ong, N. R.; Sauli, Z.; Kirtsaeng, S.; Sakuntasathien, S.; Paitong, P.; Alcain, J. B.; Lai, S. L.; Retnasamy, V.

2017-09-01

Breast cancer is one of the commonest cancers diagnosed among women around the world. Simulation approach has been utilized to study, characterize and improvise detection methods for breast cancer. However, minimal simulation work has been done to evaluate the surface stress of the breast with lumps. Thus, in this work, simulation analysis was utilized to evaluate and assess the breast surface stress due to the presence of a lump within the internal structure of the breast. The simulation was conducted using the Elmer software. Simulation results have confirmed that the presence of a lump within the breast causes stress on the skin surface of the breast.

Tapping mode AFM study on the surface dynamics of a single glucose oxidase molecule on a Au(1 1 1) surface in water with implication for a surface-induced unfolding pathway

International Nuclear Information System (INIS)

Otsuka, Ichiro; Yaoita, Masashi; Higano, Michi; Nagashima, Seiiichi; Kataoka, Ryoichi

2004-01-01

We have investigated a surface-induced unfolding dynamics of a single glucose oxidase (GO) molecule on Au(1 1 1) in air-saturated water, using tapping mode atomic force microscopy (TMAFM). We followed the unfolding process by measuring the maximum height of a well-isolated GO molecule on a terrace near a step-edge of the surface as a function of contact time. We find three linear portions with two intersections in a power-law fit to the selected values of the observed heights. The kinetic TMAFM result implies that there exist at least two distinct dynamic regimes in the unfolding

Surface-site-selective study of valence electronic structures of clean Si(100)-2x1 using Si-L23VV Auger electron-Si-2p photoelectron coincidence spectroscopy

International Nuclear Information System (INIS)

Kakiuchi, Takuhiro; Nagaoka, Shinichi; Hashimoto, Shogo; Fujita, Narihiko; Tanaka, Masatoshi; Mase, Kazuhiko

2010-01-01

Valence electronic structures of a clean Si(100)-2x1 surface are investigated in a surface-site-selective way using Si-L 23 VV Auger electron-Si-2p photoelectron coincidence spectroscopy. The Si-L 23 VV Auger electron spectra measured in coincidence with Si-2p photoelectrons emitted from the Si up-atoms or Si 2nd-layer of Si(100)-2x1 suggest that the position where the highest density of valence electronic states located in the vicinity of the Si up-atoms is shifted by 0.8 eV towards lower binding energy relative to that in the vicinity of the Si 2nd-layer. Furthermore, the valence band maximum in the vicinity of the Si up-atoms is indicated to be shifted by 0.1 eV towards lower binding energy relative to that in the vicinity of the Si 2nd-layer. These results are direct evidence of the transfer of negative charge from the Si 2nd-layer to the Si up-atoms. (author)

Designing Pulse Laser Surface Modification of H13 Steel Using Response Surface Method

Science.gov (United States)

Aqida, S. N.; Brabazon, D.; Naher, S.

2011-01-01

This paper presents a design of experiment (DOE) for laser surface modification process of AISI H13 tool steel in achieving the maximum hardness and minimum surface roughness at a range of modified layer depth. A Rofin DC-015 diffusion-cooled CO2 slab laser was used to process AISI H13 tool steel samples. Samples of 10 mm diameter were sectioned to 100 mm length in order to process a predefined circumferential area. The parameters selected for examination were laser peak power, overlap percentage and pulse repetition frequency (PRF). The response surface method with Box-Behnken design approach in Design Expert 7 software was used to design the H13 laser surface modification process. Metallographic study and image analysis were done to measure the modified layer depth. The modified surface roughness was measured using two-dimensional surface profilometer. The correlation of the three laser processing parameters and the modified surface properties was specified by plotting three-dimensional graph. The hardness properties were tested at 981 mN force. From metallographic study, the laser modified surface depth was between 37 μm and 150 μm. The average surface roughness recorded from the 2D profilometry was at a minimum value of 1.8 μm. The maximum hardness achieved was between 728 and 905 HV0.1. These findings are significant to modern development of hard coatings for wear resistant applications.

Laser spectroscopy and photochemistry on metal surfaces, pt.2

CERN Document Server

Dai, HL

1995-01-01

Using lasers to induce and probe surface processes has the advantages of quantum state specificity, species selectivity, surface sensitivity, fast time-resolution, high frequency resolution, and accessibility to full pressure ranges. These advantages make it highly desirable to use light to induce, control, or monitor surface chemical and physical processes. Recent applications of laser based techniques in studying surface processes have stimulated new developments and enabled the understanding of fundamental problems in energy transfer and reactions. This volume will include discussions on sp

Laser spectroscopy and photochemistry on metal surfaces, pt.1

CERN Document Server

Dai, HL

1995-01-01

Using lasers to induce and probe surface processes has the advantages of quantum state specificity, species selectivity, surface sensitivity, fast time-resolution, high frequency resolution, and accessibility to full pressure ranges. These advantages make it highly desirable to use light to induce, control, or monitor surface chemical and physical processes. Recent applications of laser based techniques in studying surface processes have stimulated new developments and enabled the understanding of fundamental problems in energy transfer and reactions. This volume will include discussions on sp

Wipe sampling of amphetamine-type stimulants and recreational drugs on selected household surfaces with analysis by ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry

International Nuclear Information System (INIS)

Madireddy, Sri Bharat; Bodeddula, Vanaja Reddy; Mansani, Sravan Kumar; Wells, Martha J.M.; Boles, Jeffrey O.

2013-01-01

Highlights: • Degree of sorption of eight drugs on eleven countertop surfaces was investigated. • Surface composition, volatility and solvent composition played a role in sorption. • Solvent-dependent migration was a key factor of consideration during remediation. • SPME-assisted volatility studies provided evidence for varying degrees of recovery. • Rapid three minute UPLC-QTOF method was developed to quantify the eight compounds. -- Abstract: Sorption characteristics of eight drugs related to recreational and clandestine activity—amphetamine, cocaine, heroin, N-formyl amphetamine, N-formyl methamphetamine, methamphetamine, 3, 4-methylenedioxymethamphetamine (MDMA), and pseudoephedrine—were evaluated on selected kitchen countertop surfaces. Methanol-dampened Whatman™ 40 filter paper wipes were used to collect samples from eleven surfaces including alkyd resin, ceramic tiles, glass, granite, laminate, limestone, marble, quartz compac, quartz real, soap stone, and stainless steel. The filter paper wipes were analyzed by a rapid three-minute UPLC-QTOF method, following ammonium acetate buffer (pH 5.8–6.2) extraction. The average percentage recoveries after 15 h of exposure to the surface materials tested, was found to be highest for cocaine and MDMA and lowest for amphetamine and methamphetamine. Among the eleven countertop surfaces, overall recoveries for marble were observed to be the least, whereas soapstone, quartz compac and stainless steel were among the highest. Scanning electron microscopic images of the surfaces provided a unique view of surface irregularities that potentially influenced drug recovery. Aging, migration, solvent composition, and volatility were examined. The variation in recovery of drugs was attributed to four key factors: compound volatility, surface composition, surface—compound interaction, and solvent composition

Wipe sampling of amphetamine-type stimulants and recreational drugs on selected household surfaces with analysis by ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry

Energy Technology Data Exchange (ETDEWEB)

Madireddy, Sri Bharat; Bodeddula, Vanaja Reddy; Mansani, Sravan Kumar; Wells, Martha J.M.; Boles, Jeffrey O., E-mail: jboles@tntech.edu

2013-06-15

Highlights: • Degree of sorption of eight drugs on eleven countertop surfaces was investigated. • Surface composition, volatility and solvent composition played a role in sorption. • Solvent-dependent migration was a key factor of consideration during remediation. • SPME-assisted volatility studies provided evidence for varying degrees of recovery. • Rapid three minute UPLC-QTOF method was developed to quantify the eight compounds. -- Abstract: Sorption characteristics of eight drugs related to recreational and clandestine activity—amphetamine, cocaine, heroin, N-formyl amphetamine, N-formyl methamphetamine, methamphetamine, 3, 4-methylenedioxymethamphetamine (MDMA), and pseudoephedrine—were evaluated on selected kitchen countertop surfaces. Methanol-dampened Whatman™ 40 filter paper wipes were used to collect samples from eleven surfaces including alkyd resin, ceramic tiles, glass, granite, laminate, limestone, marble, quartz compac, quartz real, soap stone, and stainless steel. The filter paper wipes were analyzed by a rapid three-minute UPLC-QTOF method, following ammonium acetate buffer (pH 5.8–6.2) extraction. The average percentage recoveries after 15 h of exposure to the surface materials tested, was found to be highest for cocaine and MDMA and lowest for amphetamine and methamphetamine. Among the eleven countertop surfaces, overall recoveries for marble were observed to be the least, whereas soapstone, quartz compac and stainless steel were among the highest. Scanning electron microscopic images of the surfaces provided a unique view of surface irregularities that potentially influenced drug recovery. Aging, migration, solvent composition, and volatility were examined. The variation in recovery of drugs was attributed to four key factors: compound volatility, surface composition, surface—compound interaction, and solvent composition.

Site selection and evaluation studies of the Waste Isolation Pilot Plant (WIPP), Los Medanos, Eddy County, NM

International Nuclear Information System (INIS)

Griswold, G.B.

1977-12-01

Bedded-salt deposits of the Salado Formation have been selected for evaluation for a proposed Waste Isolation Pilot Plant (WIPP) to be located in Eddy County, NM, approximately 26 mi east of Carlsbad. Site selection and evaluation studies that included geologic mapping, geophysical surveys, drilling, and resource appraisal were conducted over and under the prospective location. The lower portion of the Salado meets essential criteria for waste isolation. Beds chosen for waste storage lie 2074 to 2730 ft below the surface. High-purity salt exists at these depths, and the geologic structure revealed by geophysical surveys indicates that these beds are essentially flat. Additional geophysical surveys are now under way. The initial interpretation of the new data indicates that more structure may exist in the salt beds in the northern portion of the site area. Full evaluation of potentially commercial deposits of potash and natural gas within the WIPP site will be reported by separate studies, as will be the hydrologic details of the region

[Study on Hollow Brick Wall's Surface Temperature with Infrared Thermal Imaging Method].

Science.gov (United States)

Tang, Ming-fang; Yin, Yi-hua

2015-05-01

To address the characteristic of uneven surface temperature of hollow brick wall, the present research adopts soft wares of both ThermaCAM P20 and ThermaCAM Reporter to test the application of infrared thermal image technique in measuring surface temperature of hollow brick wall, and further analyzes the thermal characteristics of hollow brick wall, and building material's impact on surface temperature distribution including hollow brick, masonry mortar, and so on. The research selects the construction site of a three-story-high residential, carries out the heat transfer experiment, and further examines the exterior wall constructed by 3 different hollow bricks including sintering shale hollow brick, masonry mortar and brick masonry. Infrared thermal image maps are collected, including 3 kinds of sintering shale hollow brick walls under indoor heating in winter; and temperature data of wall surface, and uniformity and frequency distribution are also collected for comparative analysis between 2 hollow bricks and 2 kinds of mortar masonry. The results show that improving heat preservation of hollow brick aid masonry mortar can effectively improve inner wall surface temperature and indoor thermal environment; non-uniformity of surface temperature decreases from 0. 6 to 0. 4 °C , and surface temperature frequency distribution changes from the asymmetric distribution into a normal distribution under the condition that energy-saving sintering shale hollow brick wall is constructed by thermal mortar replacing cement mortar masonry; frequency of average temperature increases as uniformity of surface temperature increases. This research provides a certain basis for promotion and optimization of hollow brick wall's thermal function.

The Effect of Surface Site Ensembles on the Activity and Selectivity of Ethanol Electrooxidation by Octahedral PtNiRh Nanoparticles.

Science.gov (United States)

Erini, Nina; Beermann, Vera; Gocyla, Martin; Gliech, Manuel; Heggen, Marc; Dunin-Borkowski, Rafal E; Strasser, Peter

2017-06-01

Direct ethanol fuel cells are attractive power sources based on a biorenewable, high energy-density fuel. Their efficiency is limited by the lack of active anode materials which catalyze the breaking of the C-C bond coupled to the 12-electron oxidation to CO 2 . We report shape-controlled PtNiRh octahedral ethanol oxidation electrocatalysts with excellent activity and previously unachieved low onset potentials as low as 0.1 V vs. RHE, while being highly selective to complete oxidation to CO 2 . Our comprehensive characterization and in situ electrochemical ATR studies suggest that the formation of a ternary surface site ensemble around the octahedral Pt 3 Ni 1 Rh x nanoparticles plays a crucial mechanistic role for this behavior. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

In vitro Selection and Interaction Studies of a DNA Aptamer Targeting Protein A.

Directory of Open Access Journals (Sweden)

Regina Stoltenburg

Full Text Available A new DNA aptamer targeting Protein A is presented. The aptamer was selected by use of the FluMag-SELEX procedure. The SELEX technology (Systematic Evolution of Ligands by EXponential enrichment is widely applied as an in vitro selection and amplification method to generate target-specific aptamers and exists in various modified variants. FluMag-SELEX is one of them and is characterized by the use of magnetic beads for target immobilization and fluorescently labeled oligonucleotides for monitoring the aptamer selection progress. Structural investigations and sequence truncation experiments of the selected aptamer for Protein A led to the conclusion, that a stem-loop structure at its 5'-end including the 5'-primer binding site is essential for aptamer-target binding. Extensive interaction analyses between aptamer and Protein A were performed by methods like surface plasmon resonance, MicroScale Thermophoresis and bead-based binding assays using fluorescence measurements. The binding of the aptamer to its target was thus investigated in assays with immobilization of one of the binding partners each, and with both binding partners in solution. Affinity constants were determined in the low micromolar to submicromolar range, increasing to the nanomolar range under the assumption of avidity. Protein A provides more than one binding site for the aptamer, which may overlap with the known binding sites for immunoglobulins. The aptamer binds specifically to both native and recombinant Protein A, but not to other immunoglobulin-binding proteins like Protein G and L. Cross specificity to other proteins was not found. The application of the aptamer is directed to Protein A detection or affinity purification. Moreover, whole cells of Staphylococcus aureus, presenting Protein A on the cell surface, could also be bound by the aptamer.

In vitro Selection and Interaction Studies of a DNA Aptamer Targeting Protein A.

Science.gov (United States)

Stoltenburg, Regina; Schubert, Thomas; Strehlitz, Beate

2015-01-01

A new DNA aptamer targeting Protein A is presented. The aptamer was selected by use of the FluMag-SELEX procedure. The SELEX technology (Systematic Evolution of Ligands by EXponential enrichment) is widely applied as an in vitro selection and amplification method to generate target-specific aptamers and exists in various modified variants. FluMag-SELEX is one of them and is characterized by the use of magnetic beads for target immobilization and fluorescently labeled oligonucleotides for monitoring the aptamer selection progress. Structural investigations and sequence truncation experiments of the selected aptamer for Protein A led to the conclusion, that a stem-loop structure at its 5'-end including the 5'-primer binding site is essential for aptamer-target binding. Extensive interaction analyses between aptamer and Protein A were performed by methods like surface plasmon resonance, MicroScale Thermophoresis and bead-based binding assays using fluorescence measurements. The binding of the aptamer to its target was thus investigated in assays with immobilization of one of the binding partners each, and with both binding partners in solution. Affinity constants were determined in the low micromolar to submicromolar range, increasing to the nanomolar range under the assumption of avidity. Protein A provides more than one binding site for the aptamer, which may overlap with the known binding sites for immunoglobulins. The aptamer binds specifically to both native and recombinant Protein A, but not to other immunoglobulin-binding proteins like Protein G and L. Cross specificity to other proteins was not found. The application of the aptamer is directed to Protein A detection or affinity purification. Moreover, whole cells of Staphylococcus aureus, presenting Protein A on the cell surface, could also be bound by the aptamer.

A review of the fundamental studies of the copper activation mechanisms for selective flotation of the sulfide minerals, sphalerite and pyrite.

Science.gov (United States)

Chandra, A P; Gerson, A R

2009-01-30

A review of the considerable, but often contradictory, literature examining the specific surface reactions associated with copper adsorption onto the common metal sulfide minerals sphalerite, (Zn,Fe)S, and pyrite (FeS(2)), and the effect of the co-location of the two minerals is presented. Copper "activation", involving the surface adsorption of copper species from solution onto mineral surfaces to activate the surface for hydrophobic collector attachment, is an important step in the flotation and separation of minerals in an ore. Due to the complexity of metal sulfide mineral containing systems this activation process and the emergence of activation products on the mineral surfaces are not fully understood for most sulfide minerals even after decades of research. Factors such as copper concentration, activation time, pH, surface charge, extent of pre-oxidation, water and surface contaminants, pulp potential and galvanic interactions are important factors affecting copper activation of sphalerite and pyrite. A high pH, the correct reagent concentration and activation time and a short time delay between reagent additions is favourable for separation of sphalerite from pyrite. Sufficient oxidation potential is also needed (through O(2) conditioning) to maintain effective galvanic interactions between sphalerite and pyrite. This ensures pyrite is sufficiently depressed while sphalerite floats. Good water quality with low concentrations of contaminant ions, such as Pb(2+)and Fe(2+), is also needed to limit inadvertent activation and flotation of pyrite into zinc concentrates. Selectivity can further be increased and reagent use minimised by opting for inert grinding and by carefully choosing selective pyrite depressants such as sulfoxy or cyanide reagents. Studies that approximate plant conditions are essential for the development of better separation techniques and methodologies. Improved experimental approaches and surface sensitive techniques with high spatial

Theoretical study of the surface resistivity of (111) surfaces of NixPt1-x(111) alloys

International Nuclear Information System (INIS)

Rous, P. J.

2001-01-01

A layer-Korringa - Kohn - Rostoker calculation is used to study the compositional dependence of the surface resistivity of the (111) surface of Ni x Pt 1-x (111) alloys. The compositional disorder in the bulk and at the surface is described by the coherent potential approximation. If it is assumed that the atomic planes near the (111) surface Ni x Pt 1-x have the same composition as the bulk layers, then a weak Nordheim effect is observed in the compositional dependence of the surface resistivity. However, we show that surface segregation in Ni x Pt 1-x (111) causes an inverse Nordheim dependence in the actual surface resistivity as the bulk composition is varied. [copyright] 2001 American Institute of Physics

Hydrogenation of nitriles on a well-characterized nickel surface: From surface science studies to liquid phase catalytic activity measurements

Energy Technology Data Exchange (ETDEWEB)

Gardin, Denis Emmanuel [Univ. of California, Berkeley, CA (United States)

1993-12-01

Nitrile hydrogenation is the most commonly used method for preparing diverse amines. This thesis is aimed at the mechanism and factors affecting the performance of Ni-based catalysts in nitrile hydrogenations. Surface science techniques are used to study bonding of nitriles and amines to a Ni(111) surface and to identify surface intermediates. Liquid-phase hydrogenations of cyclohexene and 1-hexene on a Pt foil were carried out successfully. Finally, knowledge about the surface structure, surface chemical bond, dynamics of surface atoms (diffusion, growth), and reactivity of metal surfaces from solid-gas interface studies, is discussed.

Interaction of low energy electrons with surface lattice vibrations. Final report

International Nuclear Information System (INIS)

Tong, S.Y.

1984-01-01

In carrying out the DOE contract, we have succeeded in constructing a new microscopic theory, with multiple scattering, for the inelastic scattering of electrons by surface vibrations. We have applied the theory to detailed studies of angle and energy variations of the inelastic cross-section for two important systems in surface physics: carbon monoxide molecules adsorbed on the (100) surface of a nickel crystal, and hydrogen atoms adsorbed on a reconstructed tungsten (100) surface. These calculations have outlined general trends that we expect to apply to a wide variety of systems. Also, we have discovered a series of new selection rules that apply to off-specular scattering. Particularly interesting are pseudo-selection rules which are not group theoretical in origin, but approximate statements that hold well when the electron scattering amplitude exhibits a slow energy variation. We have found and defined conditions for which these selection rules would hold and break down

Chromate adsorption on selected soil minerals: Surface complexation modeling coupled with spectroscopic investigation

Energy Technology Data Exchange (ETDEWEB)

Veselská, Veronika, E-mail: veselskav@fzp.czu.cz [Department of Environmental Geosciences, Faculty of Environmental Sciences, Czech University of Life Sciences Prague, Kamýcka 129, CZ-16521, Prague (Czech Republic); Fajgar, Radek [Department of Analytical and Material Chemistry, Institute of Chemical Process Fundamentals of the CAS, v.v.i., Rozvojová 135/1, CZ-16502, Prague (Czech Republic); Číhalová, Sylva [Department of Environmental Geosciences, Faculty of Environmental Sciences, Czech University of Life Sciences Prague, Kamýcka 129, CZ-16521, Prague (Czech Republic); Bolanz, Ralph M. [Institute of Geosciences, Friedrich-Schiller-University Jena, Carl-Zeiss-Promenade 10, DE-07745, Jena (Germany); Göttlicher, Jörg; Steininger, Ralph [ANKA Synchrotron Radiation Facility, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, DE-76344, Eggenstein-Leopoldshafen (Germany); Siddique, Jamal A.; Komárek, Michael [Department of Environmental Geosciences, Faculty of Environmental Sciences, Czech University of Life Sciences Prague, Kamýcka 129, CZ-16521, Prague (Czech Republic)

2016-11-15

Highlights: • Study of Cr(VI) adsorption on soil minerals over a large range of conditions. • Combined surface complexation modeling and spectroscopic techniques. • Diffuse-layer and triple-layer models used to obtain fits to experimental data. • Speciation of Cr(VI) and Cr(III) was assessed. - Abstract: This study investigates the mechanisms of Cr(VI) adsorption on natural clay (illite and kaolinite) and synthetic (birnessite and ferrihydrite) minerals, including its speciation changes, and combining quantitative thermodynamically based mechanistic surface complexation models (SCMs) with spectroscopic measurements. Series of adsorption experiments have been performed at different pH values (3–10), ionic strengths (0.001–0.1 M KNO{sub 3}), sorbate concentrations (10{sup −4}, 10{sup −5}, and 10{sup −6} M Cr(VI)), and sorbate/sorbent ratios (50–500). Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and X-ray absorption spectroscopy were used to determine the surface complexes, including surface reactions. Adsorption of Cr(VI) is strongly ionic strength dependent. For ferrihydrite at pH <7, a simple diffuse-layer model provides a reasonable prediction of adsorption. For birnessite, bidentate inner-sphere complexes of chromate and dichromate resulted in a better diffuse-layer model fit. For kaolinite, outer-sphere complexation prevails mainly at lower Cr(VI) loadings. Dissolution of solid phases needs to be considered for better SCMs fits. The coupled SCM and spectroscopic approach is thus useful for investigating individual minerals responsible for Cr(VI) retention in soils, and improving the handling and remediation processes.

Study on surface wave characteristics of free surface flow of liquid metal lithium for IFMIF

International Nuclear Information System (INIS)

Hoashi, Eiji; Sugiura, Hirokazu; Yoshihashi-Suzuki, Sachiko; Yamaoka, Nobuo; Horiike, Hiroshi; Kanemura, Takuji; Kondo, Hiroo

2011-01-01

The international fusion materials irradiation facility (IFMIF) presents an intense neutron source to develop fusion reactor materials. The free surface flow of a liquid metal Lithium (Li) is planned as a target irradiated by two deuteron beams to generate intense neutrons and it is thus important to obtain knowledge of the surface wave characteristic for the safety and the efficiency of system in the IFMIF. We have been studying on surface wave characteristics experimentally using the liquid metal Li circulation facility at Osaka University and numerically using computational fluid dynamics (CFD) code, FLUENT. This paper reports the results of the surface fluctuation, the wave height and the surface velocity in the free surface flow of the liquid metal Li examined experimentally and numerically. In the experiment, an electro-contact probe apparatus was used to obtain the surface fluctuation and the wave height, and a high speed video was used to measure the surface velocity. We resulted in knowledge of the surface wave growth mechanism. On the other hand, a CFD simulation was also conducted to obtain information on the relation of the free surface with the inner flow. In the simulation, the model included from a two-staged contraction nozzle to a flow channel with a free surface flow region and simulation results were compared with the experimental data. (author)

Cryogenic Selective Surfaces

Data.gov (United States)

National Aeronautics and Space Administration — During our Phase 1 NIAC study we discovered a novel coating we call “Solar White” that, when used in deep space, is predicted to reflect more than 99.9% of the sun’s...

Influence of World and Gravity Model Selection on Surface Interacting Vehicle Simulations

Science.gov (United States)

Madden, Michael M.

2007-01-01

A vehicle simulation is surface-interacting if the state of the vehicle (position, velocity, and acceleration) relative to the surface is important. Surface-interacting simulations perform ascent, entry, descent, landing, surface travel, or atmospheric flight. Modeling of gravity is an influential environmental factor for surface-interacting simulations. Gravity is the free-fall acceleration observed from a world-fixed frame that rotates with the world. Thus, gravity is the sum of gravitation and the centrifugal acceleration due to the world s rotation. In surface-interacting simulations, the fidelity of gravity at heights above the surface is more significant than gravity fidelity at locations in inertial space. A surface-interacting simulation cannot treat the gravity model separately from the world model, which simulates the motion and shape of the world. The world model's simulation of the world's rotation, or lack thereof, produces the centrifugal acceleration component of gravity. The world model s reproduction of the world's shape will produce different positions relative to the world center for a given height above the surface. These differences produce variations in the gravitation component of gravity. This paper examines the actual performance of world and gravity/gravitation pairs in a simulation using the Earth.

Davisson-Germer Prize in Atomic or Surface Physics Talk: Soft X-Ray Studies of Surfaces, Interfaces and Thin Films: From Spectroscopy to Ultrafast Nanoscale Movies

Science.gov (United States)

Stöhr, Joachim

2011-03-01

My talk will review the development of soft x-ray spectroscopy and microscopy and its impact on our understanding of chemical bonding, magnetism and dynamics at surfaces and interfaces. I will first outline important soft x-ray spectroscopy and microscopy techniques that have been developed over the last 30 years and their key strengths such as elemental and chemical specificity, sensitivity to small atomic concentrations, separation of charge and spin properties, spatial resolution down to the nanometer scale, and temporal resolution down to the intrinsic femtosecond timescale of atomic and electronic motions. I will then present scientific breakthroughs based on soft x-ray studies in three selected areas: the nature of molecular bonding and reactivity on metal surfaces, the molecular origin of liquid crystal alignment on surfaces, and the microscopic origin of interface-mediated spin alignments in modern magnetic devices. My talk will also cover the use of soft x-rays for revealing the temporal evolution of electronic structure, addressing the key problem of ``function,'' down to the intrinsic femtosecond time scale of charge and spin configuration changes. As examples I will present the formation and breaking of chemical bonds in surface complexes and the motion of the magnetization in magnetic devices. Work supported by the Office of Basic Energy Science of the US Department of Energy.

Studies of surface states in zinc oxide nanopowders

Science.gov (United States)

Peters, Raul Mugabe

The surface of ZnO semiconductor nanosystems is a key performance-defining factor in numerous applications. In this work we present experimental results for the surface defect-related properties of ZnO nanoscale systems. Surface photovoltage spectroscopy was used to determine the defect level energies within the band gap, the conduction vs. valence band nature of the defect-related transitions, and to probe key dynamic parameters of the surface on a number of commercially available ZnO nanopowders. In our experimental setup, surface photovoltage characterization is conducted in high vacuum in tandem with in situ oxygen remote plasma treatments. Surface photovoltage investigations of the as-received and plasma-processed samples revealed a number of common spectral features related to surface states. Furthermore, we observed significant plasma-induced changes in the surface defect properties. Ex situ positron annihilation and photoluminescence measurements were performed on the studied samples and correlated with surface photovoltage results. The average positron lifetimes were found to be substantially longer than in a bulk single crystalline sample, which is consistent with the model of grains with defect-rich surface and subsurface layers. Compression of the powders into pellets yielded reduction of the average positron lifetimes. Surface photovoltage, positron annihilation, and photoluminescence spectra consistently showed sample-to-sample differences due to the variation in the overall quality of the nanopowders, which partially obscures observation of the scaling effects. However, the results demonstrated that our approach is efficient in detecting specific surface states in nanoscale ZnO specimens and in elucidating their nature.

Theoretical study of fractal growth and stability on surface

DEFF Research Database (Denmark)

Dick, Veronika V.; Solov'yov, Ilia; Solov'yov, Andrey V.

2009-01-01

We perform a theoretical study of the fractal growing process on surface by using the deposition, diffusion, aggregation method. We present a detailed analysis of the post-growth processes occurring in a nanofractal on surface. For this study we developed a method which describes the internal...... dynamics of particles in a fractal and accounts for their diffusion and detachment. We demonstrate that these kinetic processes are responsible for the formation of the final shape of the islands on surface after the post-growth relaxation....

Adsorption of chitosan onto carbonaceous surfaces and its application: atomic force microscopy study

International Nuclear Information System (INIS)

Tan Shengnan; Liu Zhiguo; Zu Yuangang; Fu Yujie; Xing Zhimin; Zhao Lin; Sun Tongze; Zhou Zhen

2011-01-01

The adsorption of chitosan onto highly ordered pyrolytic graphite(HOPG) surfaces and its applications have been studied by atomic force microscopy (AFM). The results indicated that chitosan topography formed on the HOPG surface significantly depends on the pH conditions and its concentration for the incubation. Under strongly acidic conditions (pH -1 , chitosan formed into uniform network structures composed of fine chains. When the solution pH was changed from 3.5 to 6.5, chitosan tends to form a thicker film. Under neutral and basic conditions, chitosan changed into spherical nanoparticles, and their sizes were increased with increasing pH. Dendritic structures have been observed when the chitosan concentration was increased up to 5 mg ml -1 . In addition, the chitosan topography can also be influenced by ionic strength and the addition of different metal ions. When 0.1 M metal ions Na + , Mg 2+ , Ca 2+ and Cu 2+ were added into the chitosan solution at pH 3.0 for the incubation, network structures, branched chains, block structures and dense networks attached with many small particles were observed, respectively. The potential applications of these chitosan structures on HOPG have been explored. Preliminary results characterized by AFM and XPS indicated that the chitosan network formed on the HOPG surface can be used for AFM lithography, selective adsorption of gold nanoparticles and DNA molecules.

An experimental study on decontamination by surface condition